#include <bits/stdc++.h>
#define rep(i,n) for(int i = 0; i < (n); ++i)
#define srep(i,s,t) for (int i = s; i < t; ++i)
#define drep(i,n) for(int i = (n)-1; i >= 0; --i)
using namespace std;
typedef long long int ll;
typedef pair<int,int> P;
#define yn {puts("Yes");}else{puts("No");}
#define MAX_N 200005

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

    ll ans = 0;
    srep(i,1,1000){
        if(2*r*r < i*i){
            ans = i;
            break;
        }
    }

    ans += x + y;
    cout << ans << endl;
    return 0;
}