class RicercaBinariaRic {
    public static boolean ricBinRic (int[] v, int k) {
	return ricbin(v,k,0,v.length-1);
    }

    private static boolean ricbin(int[] v, int k, int inf, int sup) {
	if (inf >= sup) return false;
	else {
	    int med = (inf+sup)/2;
	    if (k == v[med]) return true;
	    else if (k < v[med]) return ricbin(v,k,inf,med-1);
	    else /*k > v[med]*/  return ricbin(v,k,med+1,sup);
	}
    }

}