man and ls using execl

#include<stdio.h>
#include<sys/types.h>
#include<unistd.h>
#include<stdlib.h>

	main()
	{	
		int pid;
		
		pid=fork();
		char *a = (char *)malloc(sizeof(a));
		char *b = (char *)malloc(sizeof(b));
		
		if(pid==-1)
		{printf("Error");
			 exit(1);
		}
		
		if(pid==0)
		{ printf("\nIn child process: %d",getpid());
		  sleep(3);
		  printf("\nparent id: %d",getppid());
		  sleep(5);
                  printf("\nDisplay the contents of any directory: ");
		  
		  printf("\nEnter directory: ");
			 scanf("%s",a);
			 execl("/bin/ls","ls",a,NULL);
		}
		else
		{ 	wait();
			printf("\nIn parent process: %d",getpid());
			sleep(5);
			printf("\nDisplay man page of linux commands: ");

			printf("\nEnter command: ");
			scanf("%s",b);
			execl("/usr/bin/man","man",b,NULL);
		 
		}
}