#include <iostream>
using namespace std;

int main(){
long long x,y=0,z=0,q,p,r;

cin >> r;

x=r;
q=r*r;

do{
p=q-y*y;
 while( x*x >= p && x >= 0 )x--;
z+=(x+1);
y++;
}while(y<r);

z*=4;
cout << z << endl;

return 0;
}