package main

import (
	"bufio"
	"fmt"
	"os"
	"strconv"
)

func main() {
	var N, cnt int
	sc := bufio.NewScanner(os.Stdin)
	sc.Split(bufio.ScanWords)
	sc.Scan()
	N, _ = strconv.Atoi(sc.Text())
	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++ {
			sc.Scan()
			a[i][j] = sc.Text()
		}
	}
	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
				break
			}
		}
	}
	fmt.Println(member)
}