C, if statement still executing even when false

I'm having problems with this part of my program. The idea is to find the length (double function) between two points (out of 4 for a rectangle) and then to find the area. I'm having problems though, mainly with my if(Sa >= S && S<=Sa) function. Even if I write Sa>S it still goes through every time, no matter if Sa is equal to 999999 or -1. I'm beginning to believe space is at fault here, for always sending a neutron to shoot a 0 to a 1.

Other parts of my code work. It reads from a file, but that works perfectly to a T. My code also finds the length no problem.

double RastiIlgi(int Ax, int Ay, int Bx, int By) 
{
    double x = (Bx-Ax);
    double y = (By-Ay);
    double ilgis =sqrt(x*x + y*y);
    return ilgis;
}

int main()
{
    int Ax, int Ay, int Bx, int By
    scanf("%d %d %d %d", Ax, Ay, Bx, By);
    double x, y, S, Sa=100;
    x=RastiIlgi(Ax, Ay, Bx, By);
    y=RastiIlgi(Ax, Ay, Dx, Dy);
    if(x==y)
    {
         x=RastiIlgi(Bx, By, Cx, Cy);
         y=RastiIlgi(Cx, Cy, Dx, Dy);
    }
    printf("%f %f \n", x, y);
    S=x*y;
    if(Sa >= S && S<=Sa)
    {
        Sa = S;
        printf("%f \n", S);
        printf("%f \n", Sa);
        
    }
}```