#include <iostream>
using namespace std;
typedef long long LL;

int iabs(int n){
    if(n < 0) return -n;
    return n;
}

int main(){
    LL x, y, r;
    cin >> x >> y >> r;
    LL ans = 0;
    while(ans*ans < r*r*2) ans++;
    ans += iabs(x) + iabs(y);
    cout << ans << endl;
    return 0;
}