S = input()
A = []
k = -1
for i in range(len(S)):
    if S[i] == 'c':
        k  = i

    elif S[i] == 'w':

        if len(A) > 0:
            if A[-1][2] == 0:
                A[-1][2] = i

        if k > -1:
            A.append([k, i, 0])
            k = -1 

ANS = 10**20
for a in A:
    if a[2]>0:
        ANS = min(ANS, a[2]-a[0]+1)



if ANS == 10**20:
    print(-1)
else:
    print(ANS)



# print(A)