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

int main(){

  int n=0;
  
  while(scanf("%d",&n) != EOF){
    int sum=1;
    
    for(int i=1;i<=n;i++){ 
      sum = (sum-i) + i*2;
    }

    printf("%d\n",sum);
  }

  return 0;

}