package main

import "fmt"

func main() {
	var N, cnt int
	fmt.Scan(&N)
	a := make([][]string, N, N)
	for i := 0; i < N; i++ {
		a[i] = make([]string, N, N)
	}
	for i := 0; i < N; i++ {
		for j := 0; j < N; j++ {
			fmt.Scan(&a[i][j])
		}
	}
	member := -1
	for i := 0; i < N; i++ {
		cnt = 0
		for j := 0; j < N; j++ {
			if a[j][i] == "nyanpass" {
				cnt++
			}
			if cnt == N-1 {
				if member != -1 {
					fmt.Println("-1")
					return
				}
				member = i + 1
			}
		}
	}
	fmt.Println(member)
}