Intersection of two sorted arrays having duplicate element

#include <bits/stdc++.h> 
using namespace std; 
void printIntersection(int arr1[], int arr2[], int N, int M);  
int main() 
{ 
    int T;
    cin >> T;
 
    while(T--){
        
        int N, M;
        cin >> N >> M;
        int arr1[N];
        int arr2[M];
        for(int i = 0;i<N;i++){
            cin >> arr1[i];
        }
        
        for(int i = 0;i<M;i++){
            cin >> arr2[i];
        }
        
        // Function calling 
        printIntersection(arr1, arr2, N, M); 
        
        cout << endl;
    }
    
  return 0; 
} 

void printIntersection(int a1[], int a2[], int n, int m) 
{ 
    int i=0,j=0;
    int c[1000001]={0};
    int cnt=0;
    while(i<n && j<m){
        if(a1[i]<a2[j])i++;
        else if(a1[i]>a2[j])j++;
        else{
            if(c[a1[i]]==0){
            cout<<a1[i]<<" ";
                c[a1[i]]=1;
                cnt++;
            }
            i++;
            j++;
        }
    }
    if(cnt==0)cout<<"-1";
}