2 - 4 + 6 - 8......20

import java.io.*;
public class twominusfourplussixminuseight
{
public static void main(String args[])
{ System.out.println("2-4+6-8...-20");
int a=1;
int s=0;
for(int i=2;i<=20;i+=2)
{
if(a%2!=0)
s+=i;
else
s-=i;
a++;
System.out.println(a+ " " +i+ " " +s);

}
System.out.println(s);

}
}