# yukicoder No.345 最小チワワ問題

S = input()
min_cww = 101

if S.count("c") < 1 or S.count("w") < 2:
    print(-1)
else:
    for (i, x) in enumerate(S):
        if x == "c":
            count = 0
            l = 1

            for y in S[i + 1:]:
                l += 1
                if y == "w":
                    count += 1
                    if count == 2:
                        break
            if count == 2:
                if l < min_cww:
                    min_cww = l
    print(min_cww if min_cww < 101 else -1)