import java.io.*;
import java.util.*;

class Main239 {
	
	public static void out (Object o) {
		System.out.println(o);
	}
	
	public static int solve (String[][] memo) {
		int ret = -1;
		for (int i = 0; i < memo.length; i++) {
			for (int j = 0; j < memo.length; j++) {
				String s = memo[j][i];
				if (!s.equals("nyanpass") && !s.equals("-")) break;
				if (j == memo.length - 1) {
					if (ret != -1) return -1;
					ret = i + 1;
				}
			}
		}
		return ret;
	}
	
	public static void main (String[] args) throws IOException {
		BufferedReader br = 
			new BufferedReader(new InputStreamReader(System.in));
		
		int n = Integer.parseInt(br.readLine());
		String[][] memo = new String[n][n];
		
		for (int i = 0; i < n; i++) {
			String[] line = br.readLine().split(" ");
			for (int j = 0; j < n; j++) {
				memo[i][j] = line[j];
			}
		}
		
		out(solve(memo));
		
	}
}