#include <iostream>
#include <vector>
#include <string>
#include <algorithm>
#include <cstdio>
#include <cstring>
#include <cmath>
using namespace std;
using ll = long long;

int main() {
    int l, r, m;
    cin >> l >> r >> m;
    r++;

    if (r - l >= m) {
        cout << m << endl;
    } else {
        cout << r - l << endl;
    }

    return 0;
}