void cmmdcexti(int a,int b,int &d,int&x, int &y)
{
    int r,r0,r1,x,x0,x1,y,y0,y1,q;
    r0=a;
    r1=b;
    x0=1;y0=0;
    x1=0;y1=1;
    while(r1!=0)
    {
        q=r0/r1;
        r=r0-r1*q;
        r0=r1;
        r1=r;

        x=x0-x1*q;
        x0=x1;
        x1=x;

        y=y0-y1*q;
        y0=y1;
        y1=y;
    }
    d=r0;
    x=x0;
    y=y0;
}