#include<bits/stdc++.h>
using namespace std;
long long int ans=0,l,n,m,k=INT_MIN;
int main(){
	cin>>l>>n>>m;
	if(m-n<l){
		if(n/l<m/l){
			cout<<l-1;
			return 0;
		}
		cout<<m%l;
		return 0;
	}
	for(int i=n%l;i<m-(n%l);i++){
		if(i%l>k){
			k=i%l;
		}else{
			cout<<k;
			return 0;
		}
	}
	cout<<k;
}

/**************************************************************
	Problem: 2401
	User: zhengzihao
	Language: C++
	Result: Accepted
	Time:40 ms
	Memory:2072 kb
****************************************************************/