def main():
    S = list(input())
    cww_lengthes = []
    cww_store = []
    for i in range(len(S)):
        if S[i] == 'c':
            if len(cww_store) == 1:
                cww_store[0] = i
            if len(cww_store) == 0:
                cww_store.append(i)
        if S[i] == 'w':
            if len(cww_store) == 2:
                cww_lengthes.append(i - cww_store[0] + 1)
                cww_store = []
            if len(cww_store) == 1:
                cww_store.append(i)
    print(min(cww_lengthes) if cww_lengthes else -1)


if __name__ == '__main__':
    main()