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

int main(void)
{
  int x,y;
  double r;
  double b=0.0;

  scanf("%d %d %lf",&x,&y,&r);

  //UFO上の最も遠い距離
  double distance = sqrt(x*x+y*y)+r;

  //直線と原点の距離(|b|/√2 < distance)
  while((double)abs(b)<distance*sqrt(2)){
    b = b + 1.0;
  }

  printf("%d\n",(int)ceil(b));

  return 0;

}