// This file is a "Hello, world!" in C++ language by GCC for wandbox.
#include <iostream>
#include <cstdlib>
#include <vector>
using namespace std;
int main(){
    int l , r , m;
    cin >> l >> r >> m;
    int ans;
    if(r - l + 1 >= m)ans = m;
    else ans = r - l + 1;
    cout << ans << endl;
}

// GCC reference:
//   https://gcc.gnu.org/

// C++ language references:
//   https://cppreference.com/
//   https://isocpp.org/
//   http://www.open-std.org/jtc1/sc22/wg21/

// Boost libraries references:
//   https://www.boost.org/doc/