S=input()
S=list(S)
Ch=[]
W=[]
for i in range(len(S)):
    if S[i]=="c":
        Ch.append(i)
    if S[i]=="w":
        W.append(i)
D=[]
if len(W)<2 or len(Ch)<1:
    print (-1)
else:
    i=0
    while i<len(Ch) and Ch[i]<W[len(W)-2]:
        e=0
        j=1
        while e==0 and j<len(W):
            if W[j-1]>Ch[i]:
                D.append(W[j]-Ch[i]+1)
                e=1
            j+=1
        i+=1
    D.sort()
    if len(D)>0:
        print(D[0])
    else:
        print (-1)