#include <iostream>
using namespace std;
#include <bits/stdc++.h>


int  pairCal(int arr[],int k,int n)
 {
    
    	int i,j,count=0,sum=0;
 		for(i=0,j=n-1;i<n && j>=0;i++)
	     {
	 	sum=arr[i]+arr[j];
	 	while(sum>k && i!=j)
	 	 {
	 	 	j--;
	 	 	sum=arr[i]+arr[j];
	 	 }
	 	 if(i==j)
	 	  {
	 	  	break;
	 	  }
	 	  
	 	  count+=(j-i);
	     }
	     
	     return count;
 }

int main() {
	// your code goes here
	
	int arr[]={0,1,2,3,4,5,6};
	int n;
	cin>>n;
	
    sort(arr,arr+n);
	int left;
	cin>>left;
	int right;
	cin>>right;
	
	int l=pairCal(arr,left-1,n);
	int r=pairCal(arr,right,n);
	
	cout<<r-l;
    
	
	return 0;
}