S = input()

c, cw = None, None
ans = float('inf')
for i in range(len(S)):
    if S[i] == 'c':
        c = i
    elif S[i] == 'w':
        if cw != None:
            ans = min(ans, i - cw + 1)
        if c != None:
            cw = c

print([ans, -1][ans == float('inf')])