#!/usr/bin/env python

def main():
    sl = list(input().strip())
    sw = 0
    ans = 0
    res = 200
    for s in sl:
        if s == 'c':
            sw = 1
            ans = 1
        elif sw == 1 and s == 'w':
            sw = 2
            ans += 1
        elif sw == 2 and s == 'w':
            sw = 0
            ans += 1
            res = min(ans, res)
        else:
            ans += 1
    if res == 200:
        print('-1')
    else:
        print(res)

if __name__ == '__main__':
    main()