#include <bits/stdc++.h>
#include <math.h>
using namespace std;
int main(void){
    double x,y,r;
    cin>>x>>y>>r;
    x=abs(x);
    y=abs(y);
    x+=pow(r*r/2.0,0.5);
    y+=pow(r*r/2.0,0.5);
    cout<<(int)ceil(x+y+0.00000001)<<endl;
}