#include <cstdio>
#include <cstdlib>
#include <iostream>
#include <string>
#include <cmath>
#include <algorithm>
#include <vector>
#include <queue>
#include <stack>
#include <map>
#include <set>
#include <cstring>

typedef long long ll;
using namespace std;

#define mod 1000000007
#define INF 1000000000 //(int)1e9
#define LLINF 2000000000000000000 //(ll)2e18
#define PI  3.1415926536

#define SIZE 100000

int main(){
    int n,cc=0,ans;
    bool nyanpass[100]={0};
    string s;
    
    scanf("%d",&n);
    
    for(int i=0;i<n;i++){
        for(int j=0;j<n;j++){
            cin >> s;
            if(s!="nyanpass" && s!="-"){
                nyanpass[j] = true;
            }
        }
    }
    
    for(int i=0;i<n;i++){
        if(!nyanpass[i]){
            cc++;
            ans = i+1;
        }
    }
    
    if(cc!=1){
        puts("-1");
    }else{
        printf("%d\n",ans);
    }
    
    
    return 0;
}