#include <iostream>
#include <vector>
#include <set>

using namespace std;

int main() {
	
	int n; cin >> n;
	vector<vector<string>> a(n,vector<string>(n,""));
	vector<int> arr(n,0);
	for(int i = 0; i < n; i++){
	    for(int j = 0; j < n; j++){
	        cin >> a[i][j];
	        if(a[i][j] == "nyanpass") arr[j] += 1;
	    }
	}
	bool f = false;
	
	for(int it:arr) {
		if(it == (n-1) && !f){
			f = true;
		} else if (it == (n-1) && f) {
			cout << -1;
			return 0;
		}
	}
	for(int i = 0; i < n; i++) {
	    if(arr[i] == (n-1)){
	        cout << i + 1;
	        return 0;
	    }
	}
	cout << -1;
	
	return 0;
}