void Solve()
{
io.i(out N, out M);
long ans = 0;
if (Math.Abs(N - M) > 1)
{
goto EXIT;
}
else
{
Mat mat = new Mat();
if (Math.Abs(N - M) == 0)
{
ans = (2 * (mat.newFact(N) * mat.newFact(M)) % mat.mod) % mat.mod;
}
else
{
ans = (mat.newFact(N) * mat.newFact(M)) % mat.mod;
}
}
EXIT :;
io.o(ans);
}
//void Stream() { Test(); io.writeFlush(); }
void Test()
{
//100000 100000
Mat mat = new Mat();
io.o(mat.newFact(1000000));
}
