#include<bits/stdc++.h>
using namespace std;
int main(){
    int n,l,r,k;
    cin>>n>>l>>r;
    k=2*n-1;
    while(1){
        if(k>r){
            cout<<r-k+n-1;
            break;
        }
        if(k>=l&&k<=r){
            cout<<n-1;
            break;
        }
        k+=n;
    }
    return 0;
}
/**************************************************************
	Problem: 2401
	User: linzihang
	Language: C++
	Result: Accepted
	Time:39 ms
	Memory:2072 kb
****************************************************************/