import java.util.Scanner;

public class Test {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);

		int n = sc.nextInt();
		String str = "nyanpass";
		String[][] s = new String[n][n];
		boolean[] b = new boolean[n];
		for(int i = 0; i < n; i++){
			b[i] = true;
		}
		for(int i= 0; i < n; i++){
			for(int j = 0; j < n; j++){
				s[i][j] = sc.next();
			}
		}
		for(int i = 0; i < n; i++){
			for(int j = 0; j < n; j++){
				if(i == j){
					continue;
				}
				if(b[j]){
					if(!s[i][j].equals(str)){
						b[j] = false;
					}
				}
			}
		}
		int ren = -1, cnt = n;
		for(int i = 0; i < n; i++){
			if(b[i]){
				ren = i;
			} else {
				cnt--;
			}
		}
		if(cnt > 1 || cnt == 0){
			System.out.println(-1);
		} else {
			System.out.println(ren);
		}
	}
}