n = int(input())
xy = [map(str,input().split()) for _ in range(n)]
xy = list(zip(*xy))
ans = -1
for i in range(n):
    if "nyanpass" in xy[i] and len(set(xy[i])) == 2:
        if ans == -1:
            ans = i + 1
        else:
            ans = -1
            break
print(ans)