#include <algorithm>
#include <cmath>
#include <cstdio>
#include <cstdlib>
#include <iostream>
#include <iterator>
#include <map>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <valarray>
#include <vector>

#define N 1000
#define re(i,n) for(int i=0;i<(n);i++)
#define rep(i,a,b) for(int i=(a);i<(b);i++)
#define fe(i,n,f) for_each(i,n,f)
#define bw(a,b,c) (((a)<=(b))&&((b)<=(c)))
using namespace std;

typedef long long ll;
typedef unsigned long long ull;

int main(void){
	int n;
	string s[101][101];
	cin>>n;
	re(i,n){
		re(j,n){
			cin>>s[i][j];
		}
	}

	int t=999;
	re(i,n){
		bool f=true;
		re(j,n){
			if(s[j][i]!="-"&&s[j][i]!="nyanpass")f=false;
		}
		if(f){
			if(t!=999){cout<<"-1"<<endl;return 0;}
			t=i;
		}
	}
	cout<<(t==999?-1:t+1)<<endl;

	return 0;
}