Language: C++

#include <iostream>
#include <cstring>
using namespace std;

int main(void){
    int sx, sy, tx, ty;
    cin >> sx >> sy >> tx >> ty;
    for (int i = sy, i < ty, i++) cout << "U";
    for (int i = sx, i < tx, i++) cout << "R";
    for (int i = ty, i > sy, i++) cout << "D";
    for (int i = tx, i > sx, i++) cout << "L";
    cout << "L";
    for (int i = sy, i <= ty, i++) cout << "U";
    for (int i = sx, i <= tx, i++) cout << "R";
    cout << "DR";
    for (int i = ty, i >= sy, i++) cout << "D";
    for (int i = tx, i >= sx, i++) cout << "L";
    cout << "U";
    return 0;
}


Compiler output:
a.cc: In function 'int main()':
a.cc:8:23: error: expected ';' before '<' token
    8 |     for (int i = sy, i < ty, i++) cout << "U";
      |                       ^~
      |                       ;
a.cc:8:24: error: expected primary-expression before '<' token
    8 |     for (int i = sy, i < ty, i++) cout << "U";
      |                        ^
a.cc:8:33: error: expected ';' before ')' token
    8 |     for (int i = sy, i < ty, i++) cout << "U";
      |                                 ^
      |                                 ;
a.cc:9:23: error: expected ';' before '<' token
    9 |     for (int i = sx, i < tx, i++) cout << "R";
      |                       ^~
      |                       ;
a.cc:9:24: error: expected primary-expression before '<' token
    9 |     for (int i = sx, i < tx, i++) cout << "R";
      |                        ^
a.cc:9:33: error: expected ';' before ')' token
    9 |     for (int i = sx, i < tx, i++) cout << "R";
      |                                 ^
      |                                 ;
a.cc:10:23: error: expected ';' before '>' token
   10 |     for (int i = ty, i > sy, i++) cout << "D";
      |                       ^~
      |                       ;
a.cc:10:24: error: expected primary-expression before '>' token
   10 |     for (int i = ty, i > sy, i++) cout << "D";
      |                        ^
a.cc:10:33: error: expected ';' before ')' token
   10 |     for (int i = ty, i > sy, i++) cout << "D";
      |                                 ^
      |                                 ;
a.cc:11:23: error: expected ';' before '>' token
   11 |     for (int i = tx, i > sx, i++) cout << "L";
      |                       ^~
      |                       ;
a.cc:11:24: error: expected primary-expression before '>' token
   11 |     for (int i = tx, i > sx, i++) cout << "L";
      |                        ^
a.cc:11:33: error: expected ';' before ')' token
   11 |     for (int i = tx, i > sx, i++) cout << "L";
      |                                 ^
      |                                 ;
a.cc:13:23: error: expected ';' before '<=' token
   13 |     for (int i = sy, i <= ty, i++) cout << "U";
      |                       ^~~
      |                       ;
a.cc:13:24: error: expected primary-expression before '<=' token
   13 |     for (int i = sy, i <= ty, i++) cout << "U";
      |                        ^~
a.cc:13:34: error: expected ';' before ')' token
   13 |     for (int i = sy, i <= ty, i++) cout << "U";
      |                                  ^
      |                                  ;
a.cc:14:23: error: expected ';' before '<=' token
   14 |     for (int i = sx, i <= tx, i++) cout << "R";
      |                       ^~~
      |                       ;
a.cc:14:24: error: expected primary-expression before '<=' token
   14 |     for (int i = sx, i <= tx, i++) cout << "R";
      |                        ^~
a.cc:14:34: error: expected ';' before ')' token
   14 |     for (int i = sx, i <= tx, i++) cout << "R";
      |                                  ^
      |                                  ;
a.cc:16:23: error: expected ';' before '>=' token
   16 |     for (int i = ty, i >= sy, i++) cout << "D";
      |                       ^~~
      |                       ;
a.cc:16:24: error: expected primary-expression before '>=' token
   16 |     for (int i = ty, i >= sy, i++) cout << "D";
      |                        ^~
a.cc:16:34: error: expected ';' before ')' token
   16 |     for (int i = ty, i >= sy, i++) cout << "D";
      |                                  ^
      |                                  ;
a.cc:17:23: error: expected ';' before '>=' token
   17 |     for (int i = tx, i >= sx, i++) cout << "L";
      |                       ^~~
      |                       ;
a.cc:17:24: error: expected primary-expression before '>=' token
   17 |     for (int i = tx, i >= sx, i++) cout << "L";
      |                        ^~
a.cc:17:34: error: expected ';' before ')' token
   17 |     for (int i = tx, i >= sx, i++) cout << "L";
      |                                  ^
      |                                  ;