import numpy as np

ops = {
    "AND"   : lambda x,y: np.bitwise_and(x,y),
    "OR"    : lambda x,y: np.bitwise_or(x,y),
    "NOT"   : lambda x,y: np.invert(x),
    "RSHIFT": lambda x,y: np.right_shift(x,y),
    "LSHIFT": lambda x,y: np.left_shift(x,y),
    None    : lambda x,y: x
}

UIT = type(np.uint16(1))

def propagate(out, backlink):
    if type(out) == UIT:
        regs.update( {backlink: out} )

def procinput(x):
    if x is None: return None
    if not x.isdigit(): out = regs[x]() if not type(regs[x])==UIT else regs[x]
    else: out = np.uint16(x)
    return out


def linkfunc(backlink, fromreg1, fromreg2, operator):
    def func():
        out = ops[operator]( procinput(fromreg1), procinput(fromreg2) )
        propagate(out,backlink)
        return out
    return func

def main():
    lines = [[ side.split() for side in line.strip().split("->")] for line in open("input7.dat","r").readlines()]

    regs = {}
    for line in lines:
        lside,rside = line
        toreg = rside[0]
        if   len(lside) == 1: fromreg1, fromreg2, operator = lside[0], None, None
        elif len(lside) == 2: fromreg1, fromreg2, operator = lside[1], None, lside[0]
        elif len(lside) == 3: fromreg1, fromreg2, operator = lside[0], lside[2], lside[1]
        regs.update( {toreg : linkfunc( toreg, fromreg1, fromreg2, operator)} )

    print "Contents of register 'a' is: ", regs["a"]()

main()