N = list(input())
c = N.index("c")
w = [i for i, x in enumerate(N) if x == "w"]
if w.count("w") > 1 and w.count("c") > 0:
    if c >= w[0] or c >= w[1]:
        print("-1")
    else:
        print(w[1] - c + 1)
else:
    print("-1")