/* 
 * Program to count up or down
 */
#include <stdio.h>
#include <stdlib.h>

void count(int start, int end, int incr);

/* main program */
int main(void) {
	int start, end, incr;
	printf("enter integer values for start, end, increment:\n");
	if (scanf("%d %d %d", &start, &end, &incr) != 3) {
		printf("invalid input\n");
		return EXIT_FAILURE;
	}
	if (incr == 0) {
		printf("invalid input\n");
		return EXIT_FAILURE;
	}

	count(start, end, incr);
	return EXIT_SUCCESS;
}

void count(int start, int end, int incr) {
	printf("%d\n", start);
	int next = start + incr;
	if (incr > 0) {
		if (next <= end) count(next, end, incr);
	} else if (incr < 0) {
		if (next >= end) count(next, end, incr);
	} else {
		printf("increment of 0!\n");
	}
}