/* package whatever; // don't place package name! */
import java.util.*;
import java.lang.*;
import java.io.*;
/* Name of the class has to be "Main" only if the class is public. */
class Ideone
{
{
// your code goes here
Scanner sc
= new Scanner
(System.
in); int n = sc.nextInt();
int res = fun(n);
}
public static int fun(int n){
if(n==0)
return 0; // now the process start of sending answer upward.
return n + fun(n-1);
}
}
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