#include <bits/stdc++.h> using namespace std; using lint = long long; template<class T = int> using V = vector<T>; template<class T = int> using VV = V< V<T> >; int main() { cin.tie(nullptr); ios::sync_with_stdio(false); int l, r, m; cin >> l >> r >> m, ++r; cout << min(r - l, m) << '\n'; }