#include <iostream>
#include <cstdio>
#include <vector>
#include <algorithm>
#include <utility>

using namespace std;

int main() {
	int x, y, d;

	cin >> x >> y >> d;

	int ans = 0;
	for (int i = 0; i <= d; i++) {
		if (d - i <= x && i <= y) {
			ans++;
		}
	}
	cout << ans << endl;
	return 0;
}