OJ Board

I think test cases for this problem is too weak,I write a weak solution,and got accepted ,but when I randomly test some official
test cases, my solution is wrong.... Hope admin can get test cases stronger

Hope admin can add all offical tests,I got this problem accepted on codeforces gym, the test cases are stronger,but I don't think
6s for each test case is good,because O(n*m) brute force algorithm can run to test case 28....(32 cases in total) I want to test some other solution if it is strong enough