#define _CRT_SECURE_NO_WARNINGS
#define _USE_MATH_DEFINES
#include <iostream>
#include <map>
#include <list>
#include <cstdio>
#include <cmath>
#include <cstring>
#include <string>
#include <vector>
#include <algorithm>
#include <utility>
#include <queue>
#include <iomanip>
#define INF 1050000000
#define SIZE 100001
#define MOD 1000000007

using namespace std;

int main(void)
{
	int x, y, d;
	int cnt = 0;

	cin >> x >> y >> d;


	for (int i = 0; i <= d; i++) {
		if (i <= x && d - i <= y) cnt++;
	}

	cout << cnt << endl;

	return (0);
}
/*for (int i = 0; i < n; i++) {

	}*/