# -*- coding: utf-8 -*-

S = raw_input()

hit = [-1] * 3
mn = float("inf")
for i, s in enumerate(S):
    if s == "c":
        hit[0] = i
        hit[1] = -1
    if s == "w":
        if hit[1] != -1:
            mn = min(mn, i - hit[0] + 1)
        hit[1] = i
if mn == float("inf"):
    print -1
else:
    print mn