#include using namespace std; int main(){ cout<<"Hello,World!"; }

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#include<iostream> 
using namespace std; 
int main(){ 
  int n,sum=0; 
  cin>>n; 
  for(int i=1;i<=n;++i){ 
    sum=sum+i; 
  } 
  cout<<sum; 
  return 0; 
}