#include <bits/stdc++.h>
#define int long long
using namespace std;
const int MOD = 1000000007;
using Graph = vector<vector<int>>;

signed main() {
  int L, R, M;
  cin >> L >> R >> M;
  
  if( R-L >= M ) cout << M << endl;
  else cout << R-L+1 << endl;

}