import re


def solve():
    S = input()

    p = re.compile('c[^c]*?w.*?w')
    ms = p.findall(S)
    if ms:
        ans = 114514
        for m in ms:
            ans = min(ans, len(m))
        print(ans)
    else:
        print(-1)

if __name__ == '__main__':
    solve()