def main():
    S = input()
    C = S.find('c')
    W1 = S.find('w')
    W2 = S.find('w', W1 + 1)

    if C >= 0 and W1 - C > 0:
        print(W2 - C + 1)
    else:
        print(-1)

if __name__ == '__main__':
    main()