def main():

    s = input()
    a = 1000
    w1 = w2 = -1000
    for i in range(len(s)):
        if s[i] == 'c':
            w1 = i
        elif s[i] == 'w':
            a = min(a, i - w2 + 1)
            w2 = w1
    if a == 1000:
        print(-1)
    else:
        print(a)

if __name__ == "__main__":
    main()