#include<iostream>
#include<cmath>
#include<string>

using namespace std;

int main(){
    double x,y,r;
    cin >> x >> y >> r;

    double dist;
    if(x > 0 && y > 0){
        dist = ceil(x + y + sqrt(2)*r);
    }else if(x < 0 && y > 0){
        dist = -x + y + sqrt(2)*r;
        if(dist > 0) dist = ceil(dist);
        else if(dist < 0) dist = floor(dist);
    }else if(x < 0 && y < 0){
        dist = floor(x + y - sqrt(2)*r);
    }else if(x > 0 && y < 0){
        dist = -x + y - sqrt(2)*r;
        if(dist > 0) dist = ceil(dist);
        else if(dist < 0) dist = floor(dist);
    }else if(x > 0 && y == 0){
        dist = ceil(x + sqrt(2)*r);
    }else if(x < 0 && y == 0){
        dist = floor(x - sqrt(2)*r);
    }else if(x == 0 && y > 0){
        dist = ceil(y + sqrt(2)*r);
    }else if(x == 0 && y < 0){
        dist = floor(y - sqrt(2)*r);
    }else if(x == 0 && y == 0){
        dist = ceil(sqrt(2)*r);
    }
    int ans = abs(dist);
    cout << ans << endl;
    return 0;
}