#include <iostream>
#include <cmath>

using namespace std;

int main() {
    int x, y, r;
    cin >> x >> y >> r;
    double ufo_dist = pow((x*x+y*y), 0.5) + r;
    double kekkai_dist=0;
    int n=0;
    for(;kekkai_dist<=ufo_dist;n++) {
        kekkai_dist =double(n)/pow(2, 0.5);
    }
    cout << n-1 << endl;
}