Chess board tour

#include <bits/stdc++.h>

using namespace std;

//Definitions for quicker writing
#define REP(i,a,b) for (int i = a; i < b; i++)
#define clz __builtin_clz
#define ctz __builtin_ctz
#define popct __builtin_popcount
#define PB push_back
#define MP make_pair
#define F first
#define S second

//Typedefs for quicker writing
typedef long long ll;
typedef vector<int> vi;
typedef vector<long long> vl;
typedef pair<int,int> pi;
typedef pair<long long, long long> pl;

//Max values
const long long lmx = LLONG_MAX;
const int imx = INT_MAX;

int main() {
	//IO optimization
	ios::sync_with_stdio(0);
	cin.tie(0);
	
	//Input definition
	int n;
    int m;

	//Read In
	cin >> n >> m;

	//Main part
    if ((n % 2) && (m % 2)) {
        cout << -1;
    }
    
    if (m % 2 == 0) {
        for (int i = 1; i < n; i++) {
            cout << "D";
        }
        cout << "R";
        for (int i = 1; i < n - 1; i++) {   
            cout << "U";
        }
        for (int i = 2; i < m; i += 2) {
            cout << "R";
            for (int i = 1; i < n - 1; i++) {
                cout << "D";
            }
            cout << "R";
            for (int i = 1; i < n - 1; i++) {
                cout << "U";
            }
        }
        cout << "U";
        for (int i = 1; i < m; i++) {
          cout << "L";
        }
    } else if (n % 2 == 0) {
        for (int i = 1; i < m; i++) {
          cout << "R";
        }
        cout << "D";
        for (int i = 1; i < m - 1; i++) {
          cout << "L";
        }
        for (int i = 2; i < n; i += 2) {
            cout << "D";
            for (int i = 1; i < m - 1; i++) {
                cout << "R";
            }
            cout << "D";
            for (int i = 1; i < m - 1; i++) {
                cout << "L";
            }
        }
        cout << "L";
        for (int i = 1; i < n; i++) {
          cout << "U";
        }
    }

	//Write out
	cout << "" << "\n";
		
	//Return
	return 0;

}

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: ACCEPTED

Test 4

Verdict: ACCEPTED

Test 5

Verdict: ACCEPTED

Test 6

Verdict: ACCEPTED

Test 7

Verdict: ACCEPTED

Test 8

Verdict: ACCEPTED

Test 9

Verdict: ACCEPTED

Test 10

Verdict: ACCEPTED

Test 11

Verdict: ACCEPTED

Test 12

Verdict: ACCEPTED

Test 13

Verdict: ACCEPTED

Test 14

Verdict: ACCEPTED

Test 15

Verdict: ACCEPTED

Test 16

Verdict: ACCEPTED

Test 17

Verdict: ACCEPTED

Test 18

Verdict: ACCEPTED

Test 19

Verdict: ACCEPTED

Test 20

Verdict: ACCEPTED

Test 21

Verdict: ACCEPTED

Test 22

Verdict: ACCEPTED

Test 23

Verdict: ACCEPTED

Test 24

Verdict: ACCEPTED

Test 25

Verdict: ACCEPTED

Test 26

Verdict: ACCEPTED

Test 27

Verdict: ACCEPTED

Test 28

Verdict: ACCEPTED

Test 29

Verdict: ACCEPTED

Test 30

Verdict: ACCEPTED

Test 31

Verdict: ACCEPTED

Test 32

Verdict: ACCEPTED

Test 33

Verdict: ACCEPTED

Test 34

Verdict: ACCEPTED

Test 35

Verdict: ACCEPTED

Test 36

Verdict: ACCEPTED

Test 37

Verdict: ACCEPTED

Test 38

Verdict: ACCEPTED

Test 39

Verdict: ACCEPTED

Test 40

Verdict: ACCEPTED

Test 41

Verdict: ACCEPTED

Test 42

Verdict: ACCEPTED

Test 43

Verdict: ACCEPTED

Test 44

Verdict: ACCEPTED

Test 45

Verdict: ACCEPTED

Test 46

Verdict: ACCEPTED

Test 47

Verdict: ACCEPTED

Test 48

Verdict: ACCEPTED

Test 49

Verdict: ACCEPTED

Test 50

Verdict: ACCEPTED

Test 51

Verdict: ACCEPTED

Test 52

Verdict: ACCEPTED

Test 53

Verdict: ACCEPTED

Test 54

Verdict: ACCEPTED

Test 55

Verdict: ACCEPTED

Test 56

Verdict: ACCEPTED