def main():
    S = input()
    C = S.find('c', 0, )
    if C >= 0:
        W1 = S.find('w', C + 1)
        if W1 > C:
            W2 = S.find('w', W1 + 1,)
            if W2 < 0:
                print(-1)
                return
            elif C > 0 and W1 - C > 0:
                    print(W2 - C + 1)
            elif C == 0 and W1 - C > 0:
                    print(W2 - C)
    else:
        print(-1)


if __name__ == '__main__':
    main()