#include <bits/stdc++.h>
using namespace std;
#define REP(i, n) for (int i = 0; i < (int)(n); i++)
#define FOR(i, a, b) for (int i = (a); i < (b); ++i)
typedef long long ll;
typedef pair<int, int> P;
const int INF = 100100100;
const int MOD = (int)1e9 + 7;
const double EPS = 1e-9;
struct Edge {
  ll to;
  ll cost;
};
int main() {
  int x, y, r;
  cin >> x >> y >> r;
  cout << ceil(abs(x) + abs(y) + sqrt(2) * r) << endl;
}