#include <vector>
#include <iostream>
#include <string>
#include <algorithm>
#include <iomanip>

using namespace std;

int main() {
	int x,y,d; cin >>x>>y>>d;
	int counter = 0;
	
	for (int i = 0; i <= x; i++) {
		for (int j = 0; j <= y; j++) {
			if (i + j == d)counter += 1;
			//cout << i << "," << j << endl;
		}
	}
	cout << counter << endl;
}