public class Main{

public static void main (String[] args){

int n=100;

int allnum=0;

for (int i=1;i<=n;i++) {

allnum=allnum+i;

}

//allnum=(n*(n+1))/2;

System.out.print("allnum"+allnum);

System.out.print(allnum==5050?"测试通过":"测试失败");

    }

}