Maraton

#include <bits/stdc++.h>
using namespace std;
#define all(x) x.begin(), x.end()
#define F first
#define S second
using pi=pair<int,int>;
using ii=long long;
int main()
{
    int n;
    cin >> n;
    vector<string>v(n);
    for (int i = 0; i < n; ++i) {
        cin>>v[i];
    }
    char lol = '.';
    for (int i = 0; i < n; ++i) {
        for (int j = 0; j< n; ++j) {
            if (i + 2 < n) {
                if (v[i][j] == v[i + 1][j] && v[i][j] == v[i + 2][j]) {
                    if (v[i][j] != '.')lol = v[i][j];
                }
            }
            if (j + 2 < n) {
                if (v[i][j] == v[i][j + 1] && v[i][j] == v[i][j+2]) {
                    if (v[i][j] != '.')lol = v[i][j];
                }
            }
            if (j + 2 < n && i + 2 < n) {
                if (v[i][j] == v[i + 1][j + 1] && v[i][j] == v[i + 2][j + 2]) {
                    if (v[i][j] != '.')lol = v[i][j];
                }
            }
            if (j - 2 >= 0 && i + 2 < n) {
                if (v[i][j] == v[i + 1][j - 1] && v[i][j] == v[i + 2][j - 2]) {
                    if (v[i][j] != '.') lol = v[i][j];
                }
            }
        }
    }
    if (lol=='.') cout << "ongoing\n";
    else cout << lol << "\n";
}

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: ACCEPTED

Test 4

Verdict: ACCEPTED

Test 5

Verdict: ACCEPTED

Test 6

Verdict: ACCEPTED

Test 7

Verdict: ACCEPTED

Test 8

Verdict: ACCEPTED

Test 9

Verdict: ACCEPTED

Test 10

Verdict: ACCEPTED