def ssX16to10(_x, _ss):
    nres = 0
    stepen = len(_x)
    for sym in _x:
        if sym == 'A':
            digit = 10
        elif sym == 'B':
            digit = 11
        elif sym ==  'C':
            digit =12
        elif sym == 'D':
            digit = 13
        elif sym == 'E':
            digit = 14
        elif sym == 'F':
            digit = 15
        else:
            digit = int(sym)
        stepen -= 1
        nres += digit * _ss ** stepen
    return nres

x = input()
ss = int(input())
print(ssX16to10(x, ss))