#include <bits/stdc++.h>
#define rep(i,n) for(long long i=0;i<(n);++i)
using namespace std;
typedef long long ll;

int main() {
	ios::sync_with_stdio(false);
	cin.tie(0);
	ll L, R, M;
	cin >> L >> R >> M;
	if (R - L + 1 >= M) cout << M << endl;
	else cout << R - L + 1 << endl;
}