package main

import (
	"fmt"
)

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