program for

#include <iostream>
using namespace std;
int main()
{
int a, n;

cout<<"Masukan angka : ";
cin>>n;

for(a=1;a<=n;a++){
    if(a%3==0)
      cout<< a<<endl;
     }else{
       cout<< a<<endl;
      }
   }
  return 0;
}