package main

import . "fmt"

func main() {
	var n int
	Scan(&n)
	b:=make([]int,n)
	for _=range b {
		for i:=range b {
			var a string
			Scan(&a)
			if a=="nyanpass" {
				b[i]++
			}
		}
	}
	var c,k int
	for i,v:=range b {
		if v==n {
			c++
			k=i+1
		}
	}
	if c==1 {
		Println(k)
	} else {
	Println(-1)
	}
}