%s A B C F
%%
<INITIAL>\n printf(" accepted\n");BEGIN INITIAL;
<INITIAL>a BEGIN A;
<INITIAL>b BEGIN B;
<A>a BEGIN INITIAL;
<A>b BEGIN C;
<A>\n BEGIN INITIAL; printf(" not accepted\n");
<B>a BEGIN C;
<B>b BEGIN INITIAL;
<B>\n BEGIN INITIAL; printf(" not accepted\n");
<C>a BEGIN B;
<C>b BEGIN A;
<C>\n BEGIN INITIAL; printf(" not accepted\n");
<A>[^ab\n] BEGIN F;
<B>[^ab\n] BEGIN F;
<C>[^ab\n] BEGIN F;
<INITIAL>[^ab\n] BEGIN F;
<F>[^\n] BEGIN F;
<F>[\n] BEGIN INITIAL;printf("Invalid Input\n");
. ;
%%
 
main()
{ printf(“Enter the String of a and b only:\n”);
yylex();
}
/*
 

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