diff --git a/Find First and Last Position of Element in Sorted Array b/Find First and Last Position of Element in Sorted Array
new file mode 100644
index 00000000..03511349
--- /dev/null
+++ b/Find First and Last Position of Element in Sorted Array	
@@ -0,0 +1,41 @@
+class Solution {
+    public int[] searchRange(int[] nums, int target) {
+        int ans[] = new int[2];
+        ans[0] = firstOcc(nums, target);
+        ans[1] = lastOcc(nums, target);
+        return ans;
+    }
+    int firstOcc(int arr[], int target){
+        int index = -1;
+        int l = 0, r = arr.length - 1;
+        int mid;
+        while(l <= r){
+            mid = (l + r)/2;
+          if(target == arr[mid])
+                index = mid;
+            if(target <= arr[mid])
+                r = mid - 1;
+            else
+                l = mid + 1;
+            
+        }
+        return index;
+    }
+  
+    int lastOcc(int arr[], int target){
+        int index = -1;
+        int l = 0, r = arr.length - 1;
+        int mid;
+        while(l <= r){
+            mid = (l + r)/2;
+           if(target == arr[mid])
+                index = mid;
+            if(target >= arr[mid])
+                l = mid + 1;
+            else
+                r = mid - 1;
+           
+        }
+        return index;
+    }
+}
diff --git a/Largest Rectangle in Histogram.java b/Largest Rectangle in Histogram.java
new file mode 100644
index 00000000..90e08920
--- /dev/null
+++ b/Largest Rectangle in Histogram.java	
@@ -0,0 +1,65 @@
+class Solution {
+    public int largestRectangleArea(int[] arr) {
+        int n= arr.length;
+        int l[] = new int[n];
+int r[] = new int[n];
+
+// int n = sc.nextInt();
+for(int i=0; i<n; i++) {
+// arr[i]=sc.nextInt();
+l[i]=-1;
+r[i]=n;
+}
+
+Stack<Integer> st = new Stack<Integer>();
+for(int i=0; i<n; i++){
+if(st.empty()){
+    st.push(i);
+}
+else{
+while(!st.empty() && arr[i]<arr[st.peek()]){
+
+    r[st.peek()]=i;
+    st.pop();
+
+}
+st.push(i);
+}
+}
+
+ while(!st.empty())
+        {
+            st.pop();
+        }
+
+
+for( int i=n-1; i>=0; i-- ) {
+
+
+if(st.empty()){
+    st.push(i);
+    
+}
+else{
+while(!st.empty() && arr[i]<arr[st.peek()]){
+
+    l[st.peek()]=i;
+    st.pop();
+
+}
+st.push(i);
+}
+
+}
+
+int area = 0;
+        for(int i=0;i<n;i++)
+        {
+            int width = r[i]-l[i]-1;
+            area = Math.max(area, width*arr[i]);
+            
+        }
+
+        return area;
+    }
+}
diff --git a/Maths/gcd of two numbres b/Maths/gcd of two numbres
new file mode 100644
index 00000000..24da8918
--- /dev/null
+++ b/Maths/gcd of two numbres	
@@ -0,0 +1,29 @@
+// Java program to find GCD of two numbers
+class Test
+{
+	// Recursive function to return gcd of a and b
+	static int gcd(int a, int b)
+	{
+		// Everything divides 0
+		if (a == 0)
+		return b;
+		if (b == 0)
+		return a;
+	
+		// base case
+		if (a == b)
+			return a;
+	
+		// a is greater
+		if (a > b)
+			return gcd(a-b, b);
+		return gcd(a, b-a);
+	}
+	
+	// Driver method
+	public static void main(String[] args)
+	{
+		int a = 98, b = 56;
+		System.out.println("GCD of " + a +" and " + b + " is " + gcd(a, b));
+	}
+}
diff --git a/Maximum Profit of Operating a Centennial Wheel b/Maximum Profit of Operating a Centennial Wheel
new file mode 100644
index 00000000..0ad40e7f
--- /dev/null
+++ b/Maximum Profit of Operating a Centennial Wheel	
@@ -0,0 +1,32 @@
+lass Solution {
+public:
+    int minOperationsMaxProfit(vector<int>& customers, int boardingCost, int runningCost) {
+      int c=0;
+      int rem=0;
+      int r=0;
+      int ans=0;
+     int p_max=-1;
+      for(int i=0;i<customers.size()||(rem);i++){
+        r++;
+        rem+=i<customers.size()?customers[i]:0;
+        if(rem<4)
+        {
+          c+=rem;
+          rem=0;
+        }
+        else{
+          c+=4;
+          rem-=4;
+        }
+        int p=c*boardingCost-r*runningCost;
+        if(p>p_max){
+          p_max=p;
+          ans=r;
+        }
+      }
+      if(customers.size()==1)
+        return -1;
+      
+        return p_max<0?-1:ans;
+    }
+};
diff --git a/Remove Linked List Elements.java b/Remove Linked List Elements.java
new file mode 100644
index 00000000..946db400
--- /dev/null
+++ b/Remove Linked List Elements.java	
@@ -0,0 +1,36 @@
+/**
+ * Definition for singly-linked list.
+ * public class ListNode {
+ *     int val;
+ *     ListNode next;
+ *     ListNode() {}
+ *     ListNode(int val) { this.val = val; }
+ *     ListNode(int val, ListNode next) { this.val = val; this.next = next; }
+ * }
+ */
+class Solution {
+    public ListNode removeElements(ListNode head, int val) {
+        if(head== null) return head;
+      ListNode prev= null;
+      ListNode curr= head;
+      while(curr!= null){
+        if(curr.val==val){
+              if(curr==head){
+                head= curr.next;
+                curr= head;
+              }
+              else{
+                  prev.next= curr.next;
+                curr= curr.next;
+              
+              }
+        }
+        else{
+          prev= curr;
+          curr= curr.next;
+          
+        }
+      }
+      return head;
+    }
+}
diff --git a/fibonacci numbers.js b/fibonacci numbers.js
new file mode 100644
index 00000000..77df17e0
--- /dev/null
+++ b/fibonacci numbers.js	
@@ -0,0 +1,15 @@
+<script>
+//Fibonacci Series using Recursion
+	let n = 9;
+	
+	// function returns the Fibonacci number
+	function fib(n) {
+	if (n <= 1)
+		return n;
+	return fib(n-1) + fib(n-2);
+}
+
+	//function call
+	document.write(fib(n));
+//This code is contributed by Surbhi Tyagi
+</script>