s = input()

c, w, cnt = 0, 0, 0
cww = ""

for i, v in enumerate(s):
    if v == "c":
        c = i + 1
        cww += v
    elif v == "w":
        cnt += 1
        cww += v
        if cnt == 2:
            w = i + 1
            break
        
if len(cww) == 3 and cww == "cww" and c != 0 and w != 0:
    print(w - c + 1)
else:
    print(-1)