Check if the substring is present in the string and display the count of the substring present

Given a string and a sub-string, check if the sub-string exist in the main-string and display the count of the sub-string present in the string.

#include <stdio.h>
#include<string.h>
#include<stdlib.h>
int main(void) {
   char *m,*s;
   int mlen,slen;
   int i,j,index,k,flag=1,fla=1,count=0;
    
    /* Allocate memory for the main string */
 m=(char*)malloc(sizeof(char));
 
    /* Allocate memory for the sub-string */
 s=(char*)malloc(sizeof(char));
    
    /* Get the main-string from the user */
 scanf("%s",m);
    
    /* Get the sub-string from the user */
 scanf("%s",s);
    
    /* Calculate the length of the main string */
 mlen=strlen(m);
        
    /* Calculate the length of the sub-string */
 slen=strlen(s);
 
    /* Open the main-string window */
 for(i=0;i<mlen;i++)
   {
    
     flag=1;
     fla=1;
     /* If the first character of the sub-string matches with any of the character anywhere in the main string */
   if(*(m+i)==*s)
     {
      /* Copy the index where the first character of the sub-string matches */
     index=i;
      k=i;
            
            /* Open the window for the sub-string */
     for(j=0;j<slen;j++)
      {
             /* If the characters matches, simply increment the j pointer and k pointer which moves pointers to next character of main string and sub-string */
       if(*(m+k)==*(s+j))
         k++;
        else
        {
                 /* Else set the flag, so that atleast one character doesn't matches with main-string from the sub-string window */
        flag=0;
          break;
        }
    }
            
            /* If the flag was not set, there exists at least one index where the sub-string matches with the main string */
     if(flag)
      {
             
              /* Print the index of the sub-string match */
       printf("found at index %d\n",index);
                
                /* Keep the count of the sub-string match occurence */
       count++;
        fla=0;
      }
     }
   }
    
    /* If the sub-string have not occurred for at least one time, then print the sub-string is not found */
 if(fla)
    printf("not found");
   else
        /* Atlast print the count of the sub-string occurred in the main string. */
  printf("\nIt has occured %d times",count);
   return 0;
}