import bisect
S = input()
W = [0]
for s in S:
    if s=="w":
        W.append(W[-1]+1)
    else:
        W.append(W[-1])
ans = 10**9
for i, s in enumerate(S):
    if s=="c":
        pos = bisect.bisect_left(W, W[i]+2)
        if pos<=len(S):
            ans = min(ans, pos-i)
if ans==10**9:
    print(-1)
else:
    print(ans)