#include <bits/stdc++.h> 

using i64 = long long; 
using u64 = unsigned long long; 
using u32 = unsigned; 

using u128 = unsigned __int128; 
using i128 = __int128; 

void solve() {
	int N; std::cin >> N;

	std::vector<std::vector<std::string>> A(N);
	for(int i = 0; i < N; i ++) for(int j = 0; j < N; j ++) {
		std::string a; std::cin >> a;
		A[i].push_back(a);
	}

	int ans = -1;
	for(int i = 0; i < N; i ++) {
		bool ok = true;
		for(int j = 0; j < N; j ++) {
			if(i == j) continue;
			if(A[j][i] != "nyanpass") {
				ok = false;
				break;
			}
		}
		if(ok) {
			if(ans == -1) ans = i;
			else {
				std::cout << -1;
				return;
			}
		}
	}

	if(ans == -1) std::cout << -1;
	else std::cout << ans + 1;
} 

int main() { 
	std::ios::sync_with_stdio(false); 
	std::cin.tie(nullptr); 

	int T = 1; 
	//std::cin >> T; 

	while (T--) { 
		solve(); 
	} 
	return 0; 
}