s = input()
if "c" not in s or "w" not in s:
    print(-1)
    exit(0)
res = 1341398
slen = len(s)
while "c" in s:
    cidx = s.find("c")
    widx = s.find("w", cidx+1)
    if widx == -1 or widx == slen:
        break
    w2idx = s.find("w", widx+1)
    # print(cidx, widx, w2idx, s)
    if w2idx > 0:
        res = min(res, w2idx - cidx + 1)
    else:
        break
    s = s[cidx+1:]
    slen = len(s)
print(res if res != 1341398 else -1)