/* a binsearch, foo */

int binsearch(int x, int v[], int n) {
     int low, mid, high;

     low = 0;
     high = n - 1;
     mid = (low+high) / 2;
     while (low <= high && v[mid] != x) {
	  if (v[mid] < x) {
	       low = mid + 1;
	  } else
	       high = mid - 1;
	  mid = (low+high) / 2;
     }
     if (v[mid] == x) {
	  return mid;
     } else
	  return -1;
}