#include <iostream>
#include <cstring>
#include <cstdio>
#include <cmath>
using namespace std;
int main()
{
	long double i,ans=0,x,y,r,k,a,b;
	scanf("%Lf %Lf %Lf",&x,&y,&r);
	r+=1e-14;
	for(i=ceil(x-r);i<=floor(x+r);i+=1.0)
	{
		k=sqrt(r*r-(x-i)*(x-i));
		a=floor(y+k);b=ceil(y-k);
		ans+=a-b+1.0;
	}
	printf("%.0Lf\n",ans);
	return 0;
}

#include <bits/stdc++.h>
using namespace std;

int main()
{
  int X,Y,Z,A;
  double x,z;
  
  cin >> X >> Y >> Z;
  
  x = (double)Y / X;
  A = x * Z;
  
  while(true){
    z = (double)A / Z;
    if(z >= x) break;
    A++;
  }
  
  A--;
  
  cout << A << endl;
}