#!/usr/bin/env python3
# -*- coding: utf-8 -*-

import re


def solve(s):
    pattern = re.compile(r"c.*w.*w")
    matches = re.findall(pattern, s)
    if not matches:
        return -1
    else:
        return min(map(len, matches))


if __name__ == '__main__':
    print(solve(input()))