#define _USE_MATH_DEFINES	//M_PI(π),M_SQRT2(√2)
#include <iostream>			//std::cout, std::cin
#include <string>			//std::string,std::to_string(C++11)
#include <vector>			//std::vector
#include <valarray>			//std::valarray
#include <algorithm>		//std::sort
#include <time.h>			//localtime_s
#include <cstdlib>			//abs
#include <cmath>			//abs,std::pow,sqrt,sin,cos,round,floor,ceil
#include <fstream>			//std::ifstream,std::ofstream
#include <iomanip>			//std::setprecision,std::setw,std::setfill
#include <random>			//std::random(C++11)
#include <numeric>			//std::accumulate

int main(void) {

	//test用
	//std::ifstream in("test.txt");
	//std::cin.rdbuf(in.rdbuf());

	//const unsigned int MODULO = 1000000007;	//MODULO 10^9+7用

	int N;
	std::cin >> N;

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

	int ans = -1;
	int hit;
	for (int i = 0; i < N; i++) {
		hit = 0;
		for (int j = 0; j < N; j++) {
			if (A[j][i] == "nyanpass") {
				hit++;
			}
		}
		if (hit == N - 1) {
			if (ans == -1) {
				ans = i + 1;
			}
			else {
				ans = -1;
				break;
			}
		}
	}

	std::cout << ans << std::endl;
}