Write a C program to verify the String (a|b)*abb

#include<stdio.h>

#include<conio.h>

#include<string.h>

void main()

{

          int len,i;

          char str[50];

          clrscr();

          printf("\nEnter the String:-\n");

          gets(str);

          len=strlen(str)-1;

          if(str[len-2]=='a'&& str[len-1]=='b'&& str[len]=='b')

                   printf("Valid");

          else

                   printf("Invalid");

          getch();

}