C题提交了半天发现没开long

最开始写的dfs发现数据太大爆栈，后来看了题解半天没发现哪有问题，后来才发现没开long

import java.util.Scanner;

// 注意类名必须为 Main, 不要有任何 package xxx 信息
public class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int group = in.nextInt();
        for(int i = 0;i<group;i++){
            long n = in.nextInt();
            long m = in.nextInt();
            if(n>m){
                long temp = n;
                n = m;
                m = temp;
            }
            if(n==1){
                System.out.println(1);
            }else if(n==2){
                System.out.println((m+1)/2);
            }else if(n==3&&m==3){
                System.out.println(8);
            }else{
                System.out.println(m*n);
            }
        }
    }
}