s = str(input())
C = []
W = []
for i, c in enumerate(s):
    if c == 'c':
        C.append(i)
    if c == 'w':
        W.append(i)

import bisect
INF = 10**18
ans = INF
for ci in C:
    i = bisect.bisect_left(W, ci)
    if len(W)-i < 2:
        break
    ans = min(ans, W[i+1]-ci+1)
if ans != INF:
    print(ans)
else:
    print(-1)