N = int(input())
first_line = input().split()
renchyon_ppoi_idx = [i for i, v in enumerate(first_line) if v == 'nyanpass']
for x in range(N-1):
    nex_line = input().split()
    for y in renchyon_ppoi_idx:
       if nex_line[y] != 'nyannpass':
           renchyon_ppoi_idx.remove(y)
if len(lis)==0:print(-1)
else: print(lis[0])