package me.yukicoder.lv1;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;


public class No0239 {
	public static void main(String[] args) {
		try (BufferedReader br = new BufferedReader(new InputStreamReader(System.in))) {
			int N = Integer.parseInt(br.readLine());
			String[][] greet = new String[N][N];
			int ans = -1;

			for (int i = 0; i < N; i++) {
				String[] str = br.readLine().split(" ");
				for (int j = 0; j < N; j++) {
					greet[i][j] = str[j];
				}
			}

			for (int j = 0; j < N; j++) {
				int cnt = 0;
				for (int i = 0; i < N; i++) {
					if (i != j) {
						cnt = greet[i][j].equals("nyanpass") ? cnt + 1 : cnt;
					}
				}
				if (cnt == N - 1) {
					if (ans == -1) {
						ans = j + 1;
					} else {
						ans = -1;
					}
				}
			}
			System.out.println(ans);
		} catch (IOException e) {
			e.printStackTrace();
		}
	}
}