原来这就是状态转移的运用吗，受教了

import sys
mod = 2000120420010122
for s in sys.stdin:
    s = s.lower()
    c = cw = cwb = cwbc = 0
    for i in s:
        if i == 'c':
            c += 1
            cwbc = (cwbc + cwb) % mod 
        elif i == 'w':
            cw = (cw + c) % mod
        elif i == 'b':
            cwb = (cwb + cw) % mod
    print(cwbc)