s = input()

n = len(s)

flg = False
for i in range(n-3):
    #print(s[i:i+4])
    if s[i:i+4] == 'pain':
        flg = True
        f = i
        break

if not flg:
    print(-1)
    exit()

c = s[:f].count('pon')

if c < 2:
    print(-1)
    exit()

print(c-1)