#include<iostream>
#include<cstdio>
#include<vector>
#include<algorithm>
#include<string>
using namespace std;
int main(){
    int N,count=0,ans;
    string s[100][100];
    bool flag;
    cin >> N;
    for(int i=0;i<N;i++){
        for(int j=0;j<N;j++){
            cin >> s[i][j];
        }
    }
    for(int j=0;j<N;j++){
        if(s[0][j]=="nyanpass"||s[0][j]=="-"){
            flag=1;
            for(int i=1;i<N;i++){
                if(i!=j&&s[i][j]!="nyanpass")   flag=0;
            }
            if(flag){
                ans = j;
                count++;
            }
        }
    }
    if(count==1)    cout << ++ans;
    else    cout << "-1";
    return 0;
}