#!/usr/bin/env python
#coding:utf8

def read():
    return raw_input()


def work(s):
    s = s[::-1]

    ans = 1 << 30
    
    wList = []
    for i in range(len(s)):
        if s[i] == 'w':
            wList.append(i)
        elif s[i] == 'c' and len(wList) >= 2:
            ans = min(ans, i - wList[-2] + 1)

    print -1 if ans == 1 << 30 else ans


if __name__ == "__main__":
    work(read())