; To corroborate that s is uniformly distributed on [0, 1].
#include <stdio.h>
#include <stdlib.h>
#define c 50
typedef double R;
R scale = 0x1.p-30;
R rn(){return scale*random() - 1.0;}
int main(){int A[c]; for(int j=0; j<c; ++j) A[j]=0;
int out = 0;
for(int j=0; j<10; ++j) printf("%7.4f ", rn()); printf("\n");
for(int j=0; j<1000000; ++j) {R x = rn(), y = rn();
    {R s = x*x + y*y;
     if(s<1.0) {int u = s*c; ++A[u];} else ++out;}}
for(int j=0; j<c; ++j) printf("%3d %6d\n", j, A[j]);
printf("out: %d\n", out);
return 0;}

/*
 0.6804 -0.2112  0.5662  0.5969  0.8233 -0.6049 -0.3296  0.5365 -0.4445  0.1079 
  0  15590
  1  15892
  2  15857
  3  15665
  4  15683
  5  15577
  6  15908
  7  15844
  8  15789
  9  15838
 10  15849
 11  15704
 12  15705
 13  15793
 14  15688
 15  15611
 16  15856
 17  15662
 18  15759
 19  15951
 20  15565
 21  15686
 22  15575
 23  15712
 24  15941
 25  15469
 26  15853
 27  15653
 28  15843
 29  15537
 30  15753
 31  15628
 32  15642
 33  15622
 34  15845
 35  15637
 36  15688
 37  15480
 38  15562
 39  15720
 40  15719
 41  15716
 42  15832
 43  15818
 44  15564
 45  15663
 46  15577
 47  15675
 48  15836
 49  15686
out: 214282
*/