# No.239 にゃんぱすー
n = int(input())
a = [input().split() for i in range(n)]
villegers = [0] * n

for i in range(n):
     if a[0][i] == 'nyanpass' or a[0][i] == '-':
        candidate = i
        for j in range(n):
            if j != i and a[j][i] != 'nyanpass':
                candidate = -1
                break
        
        if candidate != - 1:
            villegers[candidate] = 1

print(villegers.index(1) + 1 if villegers.count(1) == 1 else -1)