import numpy as np

N=int(input())
a = [input().split() for l in range(N)]

b=np.array(a).T.tolist()

flag_list=[]
for i in b:
    flag=True
    for j in i:
        if j!='-' and j!='nyanpass':
            flag=False
            break
    flag_list.append(flag)

if flag_list.count(True)==1:
    print(flag_list.index(True)+1)
else:
    print(-1)