n = int(input())
result = []
for i in range(n):
    an = input().split()
    result.append(an)
result = [list(set(filter(lambda x :x!="-",list(i)))) for i in zip(*result)]
answer = []
for i,v in enumerate(result):
    if len(v)==1 and v[0]=="nyanpass":
        answer.append(i+1)
print(answer[0]) if len(answer)==1 else print(-1)