Sas Monte Carlo Unit Circle

data test;
	Do i=1 to 10000;
		Do While x^2 + b^2 <1;
			x=2*ranuni(111)-1;
			y=2*ranuni(111)-1;
	 		z= x^2 + b^2 <1;
		end;
		output;
	end;
run;
ods graphics on;
proc bivariatete data=test;
      var x;
      var y;
	  var z;
      histogram z;
  run;
ods graphics off;