import java.io.*;
class SumofNSequenceNumbers
{
public static void main(String args[] )
throws IOException
{
BufferedReader k=new BufferedReader(new InputStreamReader
(System.in));
String m;
int n,s=0,i;
System.out.print("Enter the Limit : ");
m=k.readLine();
n=Integer.parseInt(m);
for(i=1;i<=n;i++)
{
s=s+i;
}
System.out.println("sum is "+s);
}
}