#include<iostream>
#include<cstdio>
#include<cstring>
#include <cstdlib>  
#include <cmath>   
#include<cctype>
#include<string>
#include<set>
#include<iomanip>
#include <map>
#include<algorithm>
#include <functional>
#include<vector>
#include<climits>
#include<stack>
#include<queue>
#include <deque>
#include <climits>
#include <typeinfo>
#include <utility> 
#define all(x) (x).begin(),(x).end()
#define rep(i,m,n) for(int i = m;i < n;++i)
#define pb push_back
#define fore(i,a) for(auto &i:a)
#define rrep(i,m,n) for(int i = m;i >= n;--i)
#define INF INT_MAX/2
using namespace std;
using ll = long long;
using R = double;
const ll MOD = 1e9 + 7;
const ll inf = 1LL << 50;
struct edge { ll from; ll to; ll cost; };


int main() {
	int a, b, s;
	cin >> a >> b >> s;

	int xa = abs(a-s);
	int xb = abs(b-s);

	if (s == 1 || xa <= xb) {
		if (a > s)cout << a << endl;
		else cout << xa + s << endl;
	}
	else {
		if (s > a) {
			if (a == 0)cout << xb + s + 1 << endl;
			cout << xb + s << endl;
		}
		else cout << xb + (s-1) + a << endl;
	}

	return 0;
}