#include <stdio.h>

/*
 * This program implements the finite state automaton example given
 * in assignment 3.
 */
int main () {
        char    input;
        int     state;

        /* the initial state is 1 */

        state = 1;

        /* get the first character from input */

        input = getchar ();

        /* while the current input character is not a dollar sign,
         * do the following code.
         */
        while (input != '$') {

                if (state == 1) {

                        /* from state 1, go to state 3 on 'a' input */

                        if (input == 'a') 
                                state = 3;

                        /* from state 1, go to state 2 on 'b' input */

                        else if (input == 'b')
                                state = 2;
                } else if (state == 2) {

                        /* from state 2, go to state 1 on 'a' input */

                        if (input == 'a') 
                                state = 1;

                        /* from state 2, go to state 2 on 'b' input */

                        else if (input == 'b')
                                state = 2;
                } else if (state == 3) {

                        /* from state 3, go to state 1 on 'a' input */

                        if (input == 'a')
                                state = 1;

                        /* from state 3, go to state 2 on 'b' input */

                        else if (input == 'b')
                                state = 2;
                }

                /* get another input character; it might be a dollar
                 * sign, the while statement will check it.
                 */

                input = getchar ();
        }

        if (state == 3)

                /* if we are in the final state, print "accepted." */

                printf ("accepted.\n");
        else
                /* if we are *not* in the final state, print "not accepted." */

                printf ("not accepted.\n");
}