Maraton

#include <bits/stdc++.h>

using namespace std;

char d[33][33];

bool same(char a, char b, char c){
    return a==b && a==c && b==c;
}

int main(){

    int n;
    cin >> n;

    for(int i=0; i<n; i++){
        for(int j=0; j<n; j++){
            cin >> d[i][j];
        }
    }

    if(n>2){
        for(int i=0; i<n; i++){
            for(int j=0; j<n; j++){
                if(d[i][j] == '.') continue;
                if(i<n-2 && same(d[i][j], d[i+1][j], d[i+2][j])){
                    cout << d[i][j];
                    return 0;
                }
                if(j<n-2 && same(d[i][j], d[i][j+1], d[i][j+2])){
                    cout << d[i][j];
                    return 0;
                }
                if(i<n-2 && j<n-2 && same(d[i][j], d[i+1][j+1], d[i+2][j+2])){
                    cout << d[i][j];
                    return 0;
                }
                if(i>1 && j<n-2 && same(d[i][j], d[i-1][j+1], d[i-2][j+2])){
                    cout << d[i][j];
                    return 0;
                }
            }
        }
    }

    cout << "ongoing";
    return 0;
}

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