#include <stdio.h>

/* Define constants for the state of the automata */
#define START 0
#define A     1
#define B     2
#define C     3
#define ESC   4
#define F     5
#define ERROR 6

int main ()
{
	int state = START;  /* We start at state START */
	int c, count = 0;
	while (1) {
		/* Read the next character into an integer, c < 0
		 * means end of input (EOF) */
		c = getchar(); count++;
		if (c < 0)
			break;
		/* First distinguish according to state */
		switch (state) {
		case START:
			switch (c) {
			case '"':
				state = A;
				break;
			case '\'':
				state = B;
				break;
			default:
				/* Nothing */
				break;
			}
			break;
		case A:
			switch (c) {
			case '%':
				state = F;
				break;
			case '\\':
				state = ESC;
				break;
			case '"':
				state = START;
				printf ("OK\n");
				break;
			default:
				/* Nothing */
				break;
			}
			break;	
		case B:
			switch (c) {
			case '\'':
				state = START;
				break;
			case '\\':
				state = C;
				break;
			default:
				/* Nothing */
				break;
			}
			break;
		case C:
			state = B;
			break;
		case ESC:
			switch (c) {
			case '"': case '\\': case 'a': case 'b': case 'f':
			case 'n': case 'r': case 't': case 'v':
				state = A;
				break;
			default:
				state = ERROR;
				break;
			}
			break;
		case F:
			switch (c) {
			case '0': case '1': case '2': case '3': case '4':
			case '5': case '6': case '7': case '8': case '9':
				/* Nothing */
				break;
			case 'd': case 'i': case 'u': case 'x': case 'X':
			case 'f': case 'e': case 'E': case 'g': case 'G':
			case 'c': case 'C': case 's': case 'S': case 'p':
			case 'n': case '\\':
				state = A;
				break;
			default:
				state = ERROR;
				break;
			}
			break;
		case ERROR:
			switch (c) {
			case '"':
				state = START;
				printf ("ERROR\n");
				break;
			default:
				/* Nothing */
				break;
			}
			break;
		default:
			fprintf (stderr, "Internal error\n");
			return 1;
		}
	}
	if (state != START) {
		printf ("Unterminated\n");
	}
	return 0;
}

/* Test cases							Output
 ************************************************************************
 * '\''								NOTHING
 * '"'								NOTHING
 * ""								OK
 * "\x"								ERROR
 * "\a%G"							OK
 * "\b%X%10909091901901901839847938745i"			OK
 * "\b%X%3m\a"							ERROR
 * "%m"								ERROR
 * "%3m"							ERROR
 * "% 4i"							ERROR
 * "%4i"							OK
 * "\\"								OK
 * "\""								OK
 * "\"\\\a\b\f\n\r\t\v%20s"					OK
 * "\"\\\a\b\f\n\r\t\v%a"					ERROR
 * "%d%i%u%x%X%f%e%E%g%G%c%C%s%S%p%1n\v\v\v\v"			OK
 * "%d%i%u%x%X%f%e%E%g%G%c%C%s%S%11111111p%1n\v\v\v\v"		OK
 * "%d%i%u%x%X%f%e%E%g%G%c%C%s%S%11111111p%1n\n\n\n\c"		ERROR
 * %d%i%u%x%X%f%e%E%g%G%c%C%s%S%11111111p%1n\n\n\n\c		NOTHING
 * ""%d%i%u%x%X%f%e%E%g%G%c%C%s%S%11111111p%1n\n\n\n		OK
 * "'"'"'"'"'"'"'"						OK (3mal)
 */