#include <bits/stdc++.h>
using namespace std;
typedef long long int ll;
#define f(a,b,c,d) for(ll a=b; a<c; a+=d)
#define MOD 1000000007
#define pb push_back
#define umap unordered_map
#define uset unordered_set
#define pq priority_queue

void solve()
{
  	ll a, b, c;
  cin >> a >> b >> c;
  cout << 21 - a - b - c;
}

signed main()
{

#ifndef ONLINE_JUDGE
    freopen("input.txt", "r", stdin);
    freopen("output.txt", "w", stdout);
#endif

    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);

    ll t = 1;
    //cin >> t;
    ll tt = t;
    while (t--)
    {
        //cout << "Case #" << tt - t << ": ";
        solve();
    }
}

#include <algorithm>
#include <array>
#include <cmath>
#include <cstdio>
#include <iostream>
#include <map>
#include <queue>
#include <set>
#include <string>
#include <vector>

using namespace std;
#define int long long
#define ll long long
#define pii std::pair<int, int>
#define pdd std::pair<double, double>
#define INF (1LL << 33)
#define REP(i, n) for (int i = 0; i < (int)(n); i++)
#define SHOW(p)                                                                \
  if (test)                                                                    \
    cout << #p " : " << p << endl;
bool test = false;
int R, X, Y;
signed main() {
  test = true;
  test = false;
  cin >> R >> X >> Y;
  if (test) {
    cout << X * X + Y * Y << endl;
  }
  if (X * X + Y * Y == R * R) {
    cout << 1 << endl;
  } else if (X * X + Y * Y <= 4 * R * R) {
    cout << 2 << endl;
  } else {
    cout << ceil(sqrt((X * X + Y * Y - 1) / (R * R) + 1)) << endl;
  }
  return 0;
}
