n = int(input())
C = [0]*n
for i in range(n):
    A = list(map(str, input().split()))
    for j, a in enumerate(A):
        if a == 'nyanpass':
            C[j] += 1
ans = []
for i in range(n):
    if C[i] == n-1:
        ans.append(i+1)
if len(ans) == 1:
    print(ans[0])
else:
    print(-1)