If I enter for example 150000 I get overflow , (y-1)x^5 passes limitation of any type.

Do I need to create new type to keep ((10^8)^5)size value ?
Or anything else I have to do with values, expression?

I solved it with that g-function.

int g(int x, int y, long long m=9973){
    long long lx=x, ly=y, lx2=(lx*lx)%m, lx3=(lx*lx2)%m, lx5=(lx2*lx3)%m;

    return ( ((ly-1)*lx5)%m + lx3 - (lx*ly)%m + (3*lx)%m + (7*ly)%m) % m;
}