Chess board tour

#include <bits/stdc++.h>

using namespace std;

#define debug(x) cerr << #x << ": " << x << endl;
#define ll long long
#define ull unsigned long long
#define vi vector<int>

int main() {
    int n, m;
    cin >> n >> m;

    if (n%2 == 1 && m%2 == 1) {
        cout << -1 << endl;
        return 0;
    }

    // Go bottom right + up
    for (int i = 0; i < n-1; i++) cout << 'D';
    for (int j = 0; j < m-1; j++) cout << 'R';
    cout << 'U';

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

    else {
        for (int j = 0; j < n/2 - 1; j++) {
            for (int i = 0; i < m-2; i++) cout << "L";
            cout << "U";
            for (int i = 0; i < m-2; i++) cout << "R";
            cout << "U";
        }
        for (int j = 0; j < m-1; j++) cout << "L";
    }

    cout << endl;


    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: WRONG ANSWER

Test 10

Verdict: ACCEPTED

Test 11

Verdict: ACCEPTED

Test 12

Verdict: ACCEPTED

Test 13

Verdict: ACCEPTED

Test 14

Verdict: ACCEPTED

Test 15

Verdict: WRONG ANSWER

Test 16

Verdict: ACCEPTED

Test 17

Verdict: ACCEPTED

Test 18

Verdict: WRONG ANSWER

Test 19

Verdict: ACCEPTED

Test 20

Verdict: ACCEPTED

Test 21

Verdict: ACCEPTED

Test 22

Verdict: WRONG ANSWER

Test 23

Verdict: ACCEPTED

Test 24

Verdict: ACCEPTED

Test 25

Verdict: WRONG ANSWER

Test 26

Verdict: ACCEPTED

Test 27

Verdict: ACCEPTED

Test 28

Verdict: WRONG ANSWER

Test 29

Verdict: WRONG ANSWER

Test 30

Verdict: ACCEPTED

Test 31

Verdict: ACCEPTED

Test 32

Verdict: ACCEPTED

Test 33

Verdict: ACCEPTED

Test 34

Verdict: WRONG ANSWER

Test 35

Verdict: ACCEPTED

Test 36

Verdict: WRONG ANSWER

Test 37

Verdict: ACCEPTED

Test 38

Verdict: ACCEPTED

Test 39

Verdict: ACCEPTED

Test 40

Verdict: WRONG ANSWER

Test 41

Verdict: ACCEPTED

Test 42

Verdict: ACCEPTED

Test 43

Verdict: WRONG ANSWER

Test 44

Verdict: ACCEPTED

Test 45

Verdict: WRONG ANSWER

Test 46

Verdict: ACCEPTED

Test 47

Verdict: ACCEPTED

Test 48

Verdict: ACCEPTED

Test 49

Verdict: WRONG ANSWER

Test 50

Verdict: ACCEPTED

Test 51

Verdict: ACCEPTED

Test 52

Verdict: ACCEPTED

Test 53

Verdict: WRONG ANSWER

Test 54

Verdict: ACCEPTED

Test 55

Verdict: ACCEPTED

Test 56

Verdict: ACCEPTED