S=input()

turn=0
cnt=0
isOK=False
ans=10**9
for i in range(len(S)):
    if turn==0:
        if S[i]=='c':
            cnt=1
            turn+=1
        else:
            cnt+=1
    elif turn==1:
        if S[i]=='w':
            cnt+=1
            turn+=1
        else:
            cnt+=1
    else:
        if S[i]=='w':
            cnt+=1
            isOK=True
            ans=min(ans,cnt)
            turn=0
        else:
            cnt+=1

print(ans if isOK else -1)