#include <algorithm>
#include <cmath>
#include <cstdio>
#include <cstdlib>
#include <functional>
#include <iostream>
#include <iterator>
#include <limits>
#include <list>
#include <map>
#include <numeric>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <utility>
#include <valarray>
#include <vector>

#define N 1000
#define MOD 1000000007
#define pe(str) return cout<<(str)<<endl,0
#define px(str) {cout<<(str)<<endl;exit(0);}
#define re(i,n) for(int i=0;i<(n);i++)
#define rep(i,a,b) for(int i=(a);i<(b);i++)
#define fe(i,n,f) for_each(i,n,f)
#define bw(a,b,c) (((a)<=(b))&&((b)<=(c)))
using namespace std;

typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;
typedef pair<int,int> pii;

int main(void){
	int a,b,r;
	cin>>a>>b>>r;
	a=abs(a);
	b=abs(b);
	int k=a+b;
	while(1){
		// int t=k+a-b-2*((k-b)*(k-b)+a*a-r*r);
		double d=fabs((double)(a+b-k)/sqrt(2));
		if((double)r<d)break;
		// cout<<d<<endl;
		// cout<<t<<endl;
		// if(t<0)break;
		k++;
	}
	cout<<k<<endl;
	return 0;
}