n = int(input())
greet = [input().split() for i in range(n)]

sorted_table = []
for i in range(n):
    greet_in_row = [row[i] for row in greet]
    sorted_table.append(greet_in_row)

nyanpass_cnt = []

for i in range(len(sorted_table)):
    l = sorted_table[i]
    l.remove("-")
    sl = set(l)
    if (len(sl) == 1) and (sl) == {"nyanpass"}:
        nyanpass_cnt.append(True)
    else:
        nyanpass_cnt.append(False)

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