#include<iostream>
#include<string>
#include<iomanip>
#include<cmath>
#include<vector>
#include<algorithm>
#include<set>

using namespace std;

#define int long long
#define rep(i,n) for(int i = 0; i < (n); i++)
#define INF ((long long)1e18)
#define MOD ((int)1e9+7)
#define endl "\n"

#define yn(f) ((f)?"Yes":"No")
#define YN(f) ((f)?"YES":"NO")

#define MAX

signed main(){
	cin.tie(0);
	ios::sync_with_stdio(false);
	cout<<fixed<<setprecision(10);
	
	int L, M, R;
	int ans = 0;
	set<int> s;
	
	cin>>L>>R>>M;
	
	// for(int i = L; i <= R; i++ ){
		// s.insert(i%M);
	// }
	
	ans = min(R-L+1,M);
	
	// cout<<s.size()<<endl;
	cout<<ans<<endl;
	
	
	return 0;
}