def main():
    s = str(input())
    n = len(s)
    stack = []
    Flag = 0
    for i in range(n):
        if i+4 <= n and s[i:i+4] == "pain":
            Flag = 1
            break
        else:
            stack.append(s[i])
    #print(stack)
    if Flag == 0:
        print(-1);exit()
    ans = 0
    while len(stack) >= 3:
        if stack[-3] == "p" and stack[-2] == "o" and stack[-1] == "n":
            ans += 1
            stack.pop()
            stack.pop()
            stack.pop()
        else:
            stack.pop()
    if ans >= 2:
        print(ans-1)
    else:
        print(-1)

if __name__ == '__main__':
    main()