Language: C

#include <stdio.h>
#include <string.h>

int main33()
{
	char s[101];
	scanf("%s",s);
	for (int i = 0; i < strlen(s); i++)
	{
		if (i+1 % 2  == 0)
		{
			if (strcmp(s[i], 'R') != 0 && strcmp(s[i], 'U') != 0 && strcmp(s[i], 'D') != 0)
			{
				printf("No");
				return 0;
			}
		}
		if (i + 1 % 2 == 1)
		{
			if (strcmp(s[i], 'L') != 0 && strcmp(s[i], 'U') != 0 && strcmp(s[i], 'D') != 0)
			{
				printf("No");
				return 0;
			}
		}
	}
	printf("Yes");
	return 0;
}

Compiler output:
main.c: In function 'main33':
main.c:12:37: error: passing argument 1 of 'strcmp' makes pointer from integer without a cast [-Wint-conversion]
   12 |                         if (strcmp(s[i], 'R') != 0 && strcmp(s[i], 'U') != 0 && strcmp(s[i], 'D') != 0)
      |                                    ~^~~
      |                                     |
      |                                     char
In file included from main.c:2:
/usr/include/string.h:156:32: note: expected 'const char *' but argument is of type 'char'
  156 | extern int strcmp (const char *__s1, const char *__s2)
      |                    ~~~~~~~~~~~~^~~~
main.c:12:42: error: passing argument 2 of 'strcmp' makes pointer from integer without a cast [-Wint-conversion]
   12 |                         if (strcmp(s[i], 'R') != 0 && strcmp(s[i], 'U') != 0 && strcmp(s[i], 'D') != 0)
      |                                          ^~~
      |                                          |
      |                                          int
/usr/include/string.h:156:50: note: expected 'const char *' but argument is of type 'int'
  156 | extern int strcmp (const char *__s1, const char *__s2)
      |                                      ~~~~~~~~~~~~^~~~
main.c:12:63: error: passing argument 1 of 'strcmp' makes pointer from integer without a cast [-Wint-conversion]
   12 |                         if (strcmp(s[i], 'R') != 0 && strcmp(s[i], 'U') != 0 && strcmp(s[i], 'D') != 0)
      |                                                              ~^~~
      |                                                               |
      |                                                               char
/usr/include/string.h:156:32: note: expected 'const char *' but argument is of type 'char'
  156 | extern int strcmp (const char *__s1, const char *__s2)
      |                    ~~~~~~~~~~~~^~~~
main.c:12:68: error: passing argument 2 of 'strcmp' makes pointer from integer without a cast [-Wint-conversion]
   12 |                         if (strcmp(s[i], 'R') != 0 && strcmp(s[i], 'U') != 0 && strcmp(s[i], 'D') != 0)
      |                                                                    ^~~
      |                                                                    |
      |                                                                    int
/usr/include/string.h:156:50: note: expected 'const char *' but argument is of type 'int'
  156 | extern int strcmp (const char *__s1, const char *__s2)
      |                                      ~~~~~~~~~~~~^~~~
main.c:12:89: error: passing argument 1 of 'strcmp' makes pointer from integer without a cast [-Wint-conversion]
   12 |                         if (strcmp(s[i], 'R') != 0 && strcmp(s[i], 'U') != 0 && strcmp(s[i], 'D') != 0)
      |                                                                                        ~^~~
      |                                                                                         |
      |                                                                                         char
/usr/include/string.h:156:32: note: expected 'const char *' but argument is of type 'char'
  156 | extern int strcmp (const char *__s1, const char *__s2)
      |                    ~~~~~~~~~~~~^~~~
main.c:12:94: error: passing argument 2 of 'strcmp' makes pointer from integer without a cast [-Wint-conversion]
   12 |                         if (strcmp(s[i], 'R') != 0 && strcmp(s[i], 'U') != 0 && strcmp(s[i], 'D') != 0)
      |                                                                                              ^~~
      |                                                                                              |
      |                                                                                              int
/usr/include/string.h:156:50: note: expected 'const char *' but argument is of type 'int'
  156 | extern int strcmp (const char *__s1, const char *__s2)
      |                                      ~~~~~~~~~~~~^~~~
main.c:20:37: error: passing argument 1 of 'strcmp' makes pointer from integer without a cast [-Wint-conversion]
   20 |                         if (strcmp(s[i], 'L') != 0 && strcmp(s[i], 'U') != 0 && strcmp(s[i], 'D') != 0)
      |                                    ~^~~
      |                                     |
      |                                     char
/usr/include/string.h:156:32: note: expected 'const char *' but argument is of type 'char'
  156 | extern int strcmp (const char *__s1, const char *__s2)
      |                    ~~~~~~~~~~~~^~~~
main.c:20:42: error: passing argument 2 of 'strcmp' makes pointer from integer without a cast [-Wint-conversion]
   20 |                         if (strcmp(s[i], 'L') != 0 && strcmp(s[i], 'U') != 0 && strcmp(s[i], 'D') != 0)
      |                                          ^~~
      |                                          |
      |                                          int
/usr/include/string.h:156:50: note: expected 'const char *' but argument is of type 'int'
  156 | extern int strcmp (const char *__s1, const char *__s2)
      |                                      ~~~~~~~~~~~~^~~~
main.c:20:63: error: passing argument 1 of 'strcmp' makes pointer from integer without a cast [-Wint-conversion]
   20 |                         if (strcmp(s[i], 'L') != 0 && strcmp(s[i], 'U') != 0 && strcmp(s[i], 'D') != 0)
      |                                                              ~^~~
      |                                                               |
      |                                                               char
/usr/include/string.h:156:32: note: expected 'const char *' but argument is of type 'char'
  156 | extern int strcmp (const char *__s1, const char *__s2)
      |                    ~~~~~~~~~~~~^~~~
main.c:20:68: error: passing argument 2 of 'strcmp' makes pointer from integer without a cast [-Wint-conversion]
   20 |                         if (strcmp(s[i], 'L') != 0 && strcmp(s[i], 'U') != 0 && strcmp(s[i], 'D') != 0)
      |                                                                    ^~~
      |                                                                    |
      |                                                                    int
/usr/include/string.h:156:50: note: expected 'const char *' but argument is of type 'int'
  156 | extern int strcmp (const char *__s1, const char *__s2)
      |                                      ~~~~~~~~~~~~^~~~
main.c:20:89: error: passing argument 1 of 'strcmp' makes pointer from integer without a cast [-Wint-conversion]
   20 |                         if (strcmp(s[i], 'L') != 0 && strcmp(s[i], 'U') != 0 && strcmp(s[i], 'D') != 0)
      |                                                                                        ~^~~
      |                                                                                         |
      |                                                                                         char
/usr/include/string.h:156:32: note: expected 'const char *' but argument is of type 'char'
  156 | extern int strcmp (const char *__s1, const char *__s2)
      |                    ~~~~~~~~~~~~^~~~
main.c:20:94: error: passing argument 2 of 'strcmp' makes pointer from integer without a cast [-Wint-conversion]
   20 |                         if (strcmp(s[i], 'L') != 0 && strcmp(s[i], 'U') != 0 && strcmp(s[i], 'D') != 0)
      |                                                                                              ^~~
      |                                                                                              |
      |                                                                                              int
/usr/include/string.h:156:50: note: expected 'const char *' but argument is of type 'int'
  156 | extern int strcmp (const char *__s1, const char *__s2)
      |                                      ~~~~~~~~~~~~^~~~