TRO CHo X O 3x3

Code

#include <bits/stdc++.h>
#define hieuhfgr ios_base::sync_with_stdio(false);cin.tie(NULL);cout.tie(NULL)
#define ll long long
#define ull unsigned long long
#define gcd __gcd
#define pb push_back
#define fi first
#define se second
#define oo 1e9
#define endl "\n"
#define FILENAME "DATA"
#define file freopen(FILENAME".inp", "r", stdin);freopen(FILENAME".out", "w", stdout)
#define file1 freopen(FILENAME".INP", "r", stdin)
using namespace std;

const ll mod = 1e9+7;
const int maxn = 1e5;
int x,y;
int winx[] = {1, 3, 7, 9};

int main(){
	hieuhfgr;
	cin >> x >> y;
	bool ok = false;
	for (auto i : winx) {
		if (i == x) {
			ok = true;
			break;
		}
	}
	if (ok) {
		if (y!= 5) cout << "X";
		else cout << "D";
	}
	else {
		if (x == 5) {
			ok = false
			for (auto i : winx) {
				if (i == y) {
					ok = true;
					break;
				}
			}
			if (ok) cout << "D";
			else cout << "X";
		}
		else {
			cout << "D";
		}
	}
	return 0;
}