#include <stdio.h>

int cmmdc(int a, int b) {

	int r;

	do {
		r = a % b;
		a = b;
		b = r;
	} while (r);

	if (a == 1) {
		return 1;
	} else {
		return 0;
	}
}

int main(void) {

	FILE * fin = fopen("fractii.in", "r");
	FILE * fout = fopen("fractii.out", "w");

	int nr, i, j, rez = 0;
	fscanf(fin, "%d", &nr);

	rez = nr * 2 - 1;
	for (i = 2; i <= nr; i++) {

		for (j = 2; j <= nr; j++) {

			if (i != j && cmmdc(i, j)) {

				printf("%d/%d ", i, j);
				rez++;

			}
		}
	}
	fprintf(fout, "%d", rez);

	fclose(fin);
	fclose(fout);
	return 0;
}