Check if the substring is present in the string

Given a string and a sub-string check if the sub-string is 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;
   m=(char*)malloc(sizeof(char));
   s=(char*)malloc(sizeof(char));
   scanf("%s",m);
   scanf("%s",s);
 mlen=strlen(m);
   slen=strlen(s);
   for(i=0;i<mlen;i++)
   {
     flag=1;
     fla=1;
     if(*(m+i)==*s)
     {
      index=i;
      k=i;
      for(j=0;j<slen;j++)
      {
        if(*(m+k)==*(s+j))
         k++;
        else
        {
          flag=0;
          break;
        }
      }
      if(flag)
      {
        printf("found at index %d\n",index);
        fla=0;
      }
     }
   }
   if(fla)
    printf("not found");
   return 0;
}