S = input()
c = None
cw = 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
if ans == float("inf") :
    print(-1)
else :
    print(ans)