#include <stdio.h>
#include <stdlib.h>

// https://www.programmingsimplified.com/c/source-code/c-program-insert-substring-into-string
//
char *substring(char *string, int position, int length) 
{
   char *pointer;
   int c;
 
   pointer = malloc(length+1);
 
   if( pointer == NULL )
       exit(EXIT_FAILURE);
 
   for( c = 0 ; c < length ; c++ ) 
      *(pointer+c) = *((string+position-1)+c);       
 
   *(pointer+c) = '\0';
 
   return pointer;
}


void insert_substring(char *a, char *b, int position)
{
   char *f, *e;
   int length;
 
   length = strlen(a);
 
   f = substring(a, 1, position - 1 );      
   e = substring(a, position, length-position+1);
 
   strcpy(a, "");
   strcat(a, f);
   free(f);
   strcat(a, b);
   strcat(a, e);
   free(e);
}

int main(int argc, char **argv)
{
	char col_start[]="\033[31;40m";
	char col_end[]="\033[37;40m";

	FILE *in=stdin;
	FILE *out=stdout;

	int i=1;

	char buf[256];
	char buf2[255];

	while(NULL!=fgets(buf,255,in))
	{

	    char *pos=strstr(buf,argv[1]);
	    if(pos)
	    {
		int p=pos-buf+1;
		int l=strlen(argv[1])+strlen(col_start);

		insert_substring(buf,col_start,p);
		insert_substring(buf,col_end,p+l);

		printf("%s",buf);
	    }

	    i++;
	}

	return EXIT_SUCCESS;
}