#include<iostream>
#include<string>
#include<vector>
#include<algorithm>
#include<cmath>
#include<stdio.h>
#include<queue>
#include <climits>
const int mod = 1e9 + 7;
const int INF = 1e9;
using namespace std;
typedef long long ll;

int main()
{
    int l,r,m;
    cin >> l >> r >> m;
    if(r - l >= m){
        cout << m;
    }else{
        cout << r - l;
    }
}