#include <bits/stdc++.h>

using ll = long long;

using namespace std;

int main()
{
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    ll l,r,m;
    cin >> l >> r >> m;

    if (r - l < m)
        cout << r - l + 1 << "\n";
    else
        cout << m << "\n";

    return 0;
}