题解 | #矩阵计算#

import java.util.Scanner;
public class Main {
    
    public static void main(String[] args) {
        
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int m = sc.nextInt();
        int sum = 0;
        for(int i = 0 ; i < n ; i++) {
            for(int j = 0 ; j < m ; j++) {
                int num = sc.nextInt();
                if(num > 0) {
                    sum += num;
                }
            }
        }
        System.out.println(sum);
    }
}