#include <iostream>
#include<utility>
#include <vector>
#include <map>
#include<string>
#include<set>
#include<queue>
#include<math.h>
#define pb push_back
#define all(x) begin(x),end(x)
#define ll long long
#define P pair<int,int>
#define lP pait<ll,ll>
using namespace std;
int main() {
    int n;
    cin>>n;
    int count{0},res{0};
    vector<int> c(n);
    vector<vector<string>> a(n,vector<string>(n));
    string s="nyanpass";
    for(int i=0;i<n;i++){
        for(int j=0;j<n;j++){
            cin>>a[i][j];
    }
}
    for(int i=0;i<n;i++){
        int f=0;
        for(int j=0;j<n;j++){
            if(a[j][i]==s) f++;
            }
        if(f==n-1) {
            count++;
            if(count==1) res=i;
        }
    }

    if(count==1) cout<<res+1<<endl;
    else cout<<-1<<endl;
    return 0;
}