#include <sstream>
#include <string>
#include <vector>
#include <map>
#include <algorithm>
#include <iostream>
#include <utility>
#include <set>
#include <cctype>
#include <queue>
#include <stack>
#include <cstdio>
#include <cstdlib>
#include <cmath>

#define INF 1000000000

using namespace std;
typedef long long ll;

int main(void) {
    int x, y, d;
    cin >> x >> y >> d;
    if (d >= y) {
        if (d-y > x) {
            cout << 0 << endl;
        } else {
            cout << x - (d-y) + 1 << endl;
        }
    } else {
        cout << min(x, d) + 1 << endl;
    }
    return 0;
}