E0064.cpp

// Problem Code: PLAYFIT

#include <iostream>
#include <string>
#include <vector>
#include <limits>

using namespace std;

string fitToPlay(vector<int> g) {
	int min, diff;
	min = g[0];
	diff = numeric_limits<int>::min();
	for (int i = 1 ; i < g.size() ; i++) {
		if (diff < g[i] - min)
			diff = g[i] - min;
		if (min > g[i])
			min = g[i];
	}
	return (diff <= 0) ? "UNFIT" : to_string(diff);
}

int main() {
	ios_base::sync_with_stdio(false);
	cin.tie(NULL);
	
	int T, N, num;
	vector<int> g;
	cin >> T;
	while (T--) {
		cin >> N;
		for (int i = 0 ; i < N ; i++) {
			cin >> num;
			g.push_back(num);
		}
		cout << fitToPlay(g) << endl;
		g.clear();
	}
	return 0;
}