Forest density

#include <iostream>
#include <vector>
#include <algorithm>
#include <limits.h>
#include <map>
#include <math.h>
#include <cstdlib>
using namespace std;
 
const int MOD = 1e9 + 7;
 
int main()
{
    int n, q;
 
    cin >> n >> q;
 
    auto forest = vector<string >(n);
 
    for (int i = 0; i < n; ++i){
        cin >> forest[i];
    }
 
    for (int i = 0; i < q; ++i){
        int sum = 0;
        int x1, x2, y1, y2;
        cin >> y1 >>x1 >>y2 >>x2;
        for (int x = x1; x <= x2; ++x){
            for (int y = y1; y <= y2; ++y)
                if (forest[y-1][x-1] == '*')
                    sum++;
        }
        cout << sum << endl;
    }
}

Test 1

Verdict: ACCEPTED

Test 2

Verdict: TIME LIMIT EXCEEDED

Test 3

Verdict: TIME LIMIT EXCEEDED