N = input()

cnd = [1] * N
for n in xrange(N):
    grts = raw_input().split()
    for i in xrange(N):
        if grts[i] != "nyanpass" and grts[i] != "-":
            cnd[i] = 0

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