n = int(input())
array=[]

for i in range(n):
    array.append(input().split())

cnt=0
suspect=[]

for i in range(n):
    for j in range(n):
        if array[j][i]=="nyanpass" or array[j][i]=="-":
            cnt+=1
        if cnt==n:
            suspect.append(i+1)
    cnt=0

if len(suspect)==1:
    print(*suspect)
else:
    print(-1)