#include <iostream>
using namespace std;

int main(){
    // FILE* fp_in = freopen("data.txt", "r", stdin);
    int n;
    cin >> n;
    bool founded[n];
    for(int i=0; i<n; i++) founded[i] = true;
    for(int i=0; i<n; i++){
        for(int j=0; j<n; j++){
            string s;
            cin >> s;
            if(s.compare("nyanpass") != 0 && s.compare("-") != 0){ 
                founded[j] = false;
            }   
        }   
    }   
    int renchon = 0;
    for(int i=0; i<n; i++){
        if(founded[i]){
            if(renchon > 0){ 
                //  特定できず
                renchon = 0;
                break;
            }   
            renchon = (i+1);
        }   
    }   
    if (renchon > 0) cout << renchon << endl;
    else cout << -1 << endl;

    return 0;
}