// No.239 にゃんぱすー
package main

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

var sc = bufio.NewScanner(os.Stdin)
var wr = bufio.NewWriter(os.Stdout)

func next() string {
	sc.Scan()
	return sc.Text()
}

func nextInt() int {
	i, _ := strconv.Atoi(next())
	return i
}

func nextFloat() float64 {
	f, _ := strconv.ParseFloat(next(), 64)
	return f
}

func nextInts(n int) []int {
	ret := make([]int, n)
	for i := 0; i < n; i++ {
		ret[i] = nextInt()
	}
	return ret
}

func nextFloats(n int) []float64 {
	ret := make([]float64, n)
	for i := 0; i < n; i++ {
		ret[i] = nextFloat()
	}
	return ret
}

func nextStrings(n int) []string {
	ret := make([]string, n)
	for i := 0; i < n; i++ {
		ret[i] = next()
	}
	return ret
}

func main() {
	sc.Split(bufio.ScanWords)
	var n = nextInt()
	var a = make([][]string, n)
	for i := 0; i < n; i++ {
		a[i] = make([]string, n)
		a[i] = nextStrings(n)
	}

	m := make(map[int]struct{})
	for j := 0; j < n; j++ {
		m[j] = struct{}{}
	}
	for k := 0; k < n; k++ {
		for l := 0; l < n; l++ {
			if a[l][k] != "-" && a[l][k] != "nyanpass" {
				delete(m, k)
				break
			}
		}
	}
	if len(m) == 1 {
		for k := range m {
			// index to 村民番号
			fmt.Println(k + 1)
		}
	} else {
		fmt.Println(-1)
	}

}