V86s2e5

#include<iostream>
using namespace std;
int a[25][25];
int main()
 {
  int n,par=2,impar=1,i,j;
  cin>>n;
  for(i=1;i<=2*n;i++)
   {
    if(i%2==0)
     {
      for(j=2*n;j>=1;j--)
       {
        a[i][j]=par;
        par=par+2;
       }
      }
      else
       {
        for(j=1;j<=2*n;j++)
         {
           a[i][j]=impar;
          impar=impar+2;
         }
        }
   }
        for(i=1;i<=2*n;i++)
         {
          for(j=1;j<=2*n;j++)
           cout<<a[i][j]<<" ";
           cout<<endl;
           }
           }