N = input()
ren = [0 for i in range(N)]
for i in range(N):
    greeting = raw_input().split()
    for j,greet in enumerate(greeting):
        if (greet == "nyanpass"):
            ren[j] += 1
            
cnt = 0
res = -1
for i in range(N):
    if (ren[i] == N - 1):
        cnt += 1
        res = i
if (res == -1 or cnt >= 2):
    print -1
else:
    print res + 1