#!/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:
        cands = [match.strip("c") for match in matches]
        return min(map(len, cands)) + 1


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