Grid

input/code.cpp: In function 'int main()':
input/code.cpp:12:9: warning: unused variable 'ai' [-Wunused-variable]
     int ai;
         ^~

#include <iostream>

using namespace std;

int main() {
    int n;
    cin >> n;

    int ar[n][n];
    int visited[n][n];
    char a;
    int ai;
    for (int i = 0; i < n; i++) {
        for (int j = 0; j < n; j++) {
            cin >> a;
            int ai = a - '0';
            ar[i][j] = ai;
            visited[i][j] = 0;
        }
    }

    int ans = 0;

    for (int i = 0; i< n; i++) {
        int all = 1;
        for (int j=0; j < n; j++){
            if (ar[i][j] == 0) {
                all = 0;
                break;
            }
        }
        if (all) {
            ans++;
            for (int k = 0; k < n; k++) {
                visited[i][k] = 1;
            }
        }
    }

    for (int i = 0; i< n; i++) {
        int all = 1;
        for (int j=0; j < n; j++){
            if (ar[j][i] == 0) {
                all = 0;
                break;
            }
        }
        if (all) {
            ans++;
            for (int k = 0; k < n; k++) {
                visited[k][i] = 1;
            }
        }
    }

    int all2 = 1;
    for (int i = 0; i < n; i++){
        for (int j = 0; j < n; j++) {
            if (visited[i][j] == 0 && ar[i][j] == 1 ) {
                all2 = 0;
                break;
            }
        }
        if (all2 == 0) {
            break;
        }
    }

    if (all2 == 0) {
        cout << "-1\n";
    } else {
        if (ans == 2*n) {
            ans = n;
        }
        cout << ans << endl;
    }

    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

Test 11

Verdict: ACCEPTED

Test 12

Verdict: ACCEPTED

Test 13

Verdict: ACCEPTED

Test 14

Verdict: ACCEPTED

Test 15

Verdict: ACCEPTED

Test 16

Verdict: ACCEPTED

Test 17

Verdict: ACCEPTED

Test 18

Verdict: ACCEPTED

Test 19

Verdict: ACCEPTED

Test 20

Verdict: ACCEPTED

Test 21

Verdict: ACCEPTED

Test 22

Verdict: ACCEPTED