s = str(input())
n = len(s)
if n < 4:
    print(-1)
    exit()

for i in range(n-3):
    if s[i:i+4] == 'pain':
        p = i
        break
else:
    print(-1)
    exit()

t = s[0:p]
ans = t.count('pon')
if ans <= 1:
    print(-1)
else:
    print(ans-1)