int FIND(F, x, n)
int F[], x;
int n;

{
    int mid, bottom=0, 
    top=n-1;
    while(bottom<=top)
    {
        mid=(bottom+top)/2;
        if (F[mid] ==x) return(1); 
        else 
            if (F[mid] < x) bottom=mid+1;
            else 
	        top=mid-1;
   	}       
    return(0);
}