#include <bits/stdc++.h>
#define rep(i, n) for (int i = 0; i < (n); ++i)
#define sz(x) int(x.size())
#define show(x) {for(auto i: x){cout << i << " ";} cout << endl;}
#define isin(x,l,r) ((l) <= (x) && (x) < (r))
using namespace std;
using ll = long long;
using pii = pair<int,int>;
using pll = pair<ll,ll>;
using tii = tuple<int,int,int>;
template<typename T>bool chmin(T&x,const T&y) {if(x>y){x=y;return 1;} else return 0;}
template<typename T>bool chmax(T&x,const T&y) {if(x<y){x=y;return 1;} else return 0;}

int main() {
    double a, b, c;
    cin >> a >> b >> c;
    ll X, Y, R;
    X = round(a * 10000);
    Y = round(b * 10000);
    R = round(c * 10000);
    ll top = (Y + R) / 10000 * 10000 + 60000;
    while (top > Y + R) top -= 10000;
    ll down = (Y-R) / 10000 * 10000 - 60000;
    while (down < Y - R) down += 10000;
    ll ans = 0;
    for (ll y = down; y <= top; y += 10000) {
        ll l = sqrt(R * R - (y - Y) * (y - Y)) + 10;
        while (l * l > R * R - (y-Y) * (y-Y)) l--;
        ll left = (X - l) / 10000 * 10000 - 60000;
        while (left < X - l) left += 10000;
        ll right = (X + l) / 10000 * 10000 + 60000;
        while (right > X + l) right -= 10000;
        if (left > right) continue;
        ans += (right - left) / 10000 + 1;
        // cout << left << ' ' << right << ' ' << l << '\n';
        // cout << ans << '\n';
    }
    cout << ans << '\n';
    return 0;
    // get dp together, ll, paraphrase, debug
}

// 07
#include <iostream>
#include <cmath>
using namespace std;
#define rep(i,n) for(int i=0;i<(n);i++)
using ll = long long;

int in(){
  double x;
  cin >> x;
  x*=10000;
  return round(x);
}

bool ok(ll dx,ll dy,ll z){
  return dx*dx+dy*dy <= z*z;
}

ll f(ll x,ll y,ll z,ll lim){
  int l=0,r=1;
  ll res = 0;
  for(int i=1e9+50000;i>=lim;i-=10000){
    while(ok(x-l*10000,i-y,z))--l;
    while(ok(r*10000-x,i-y,z))r++;
    res += r-l-1;
  }
  return res;
}

int main(){
  ll x=in(),y=in(),z=in();
  x%=10000;
  y%=10000;
  ll ans = f(x,y,z,10000);
  ans += f(x,-y,z,0);
  cout << ans << endl;
  return 0;

}