#include <stdio.h>
#include <math.h>

void d(double *x, double y) {
  double w = sqrt(y) + 1.0;
  *x = *x/w + y/w;
}

double a = 1.0, b = 2.0;

int main(void) {
  d(&a, b);
  printf("%f\n", a);
  return 0;
}