#include <iostream>
#include <cstdio>
#include <algorithm>
using namespace std;

FILE *fin,*fout;
int n,r,l,ans;

int input(){

  fscanf(fin,"%d %d %d",&n,&l,&r);  //n代表个数，r代表上界限，l代表下界限
  

}

int cal(int x,int ans){

  if(x-n<n ){
    ans=max(x-n,ans);
    if(x<r) cal(x+1,ans);

  }
  else cal(x-n,ans);
  

  return ans;
}
int main()
{
  fin=fopen("candy.in","rb");
  fout=fopen("candy.out","wb"); //标准的文件指针

  input();
  cal(l,0);

  fprintf(fout,"%d",ans);
  
  fclose(fin);fclose(fout);
  return 0;
}