N = int(input())
A = [input().split() for  _ in range(N)]

sonmin_saying = [[a[i] for j, a in enumerate(A) if i != j] for i in range(N)]
rentyonpoi = [all([gr == "nyanpass" for gr in a]) for a in sonmin_saying]

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