#include <iostream>
#include <vector>
#include <cstdio>
#include <sstream>
#include <map>
#include <string>
#include <algorithm>
#include <queue>
#include <cmath>
#include <set>
using namespace std;


int main(){
	long long x,y,d;
	cin >> x >> y >> d;
	long long ans = 0;
	long long l = max(0LL, d-y);
	long long r = min(x,d);
	if(l<=r){
		ans = r-l+1;
	}
	cout << ans << endl;
	return 0;
}