/* ( ‘_>’) */
#include <stdio.h>

#define L 28

int p, q;

int nr5(int n) {
	int div5 = 0;
	while (n >= p)
		div5 += n /= p;
	return div5;
}

int main() {
	FILE *fin, *fout;
	int pas, r;

	fin = fopen("gfact.in", "r");
	fscanf(fin, "%d%d", &p, &q);
	fclose(fin);

	pas = 1 << L;
	r = 0;
	while (pas != 0) {
		if (!(nr5(r + pas) >= q))
			r += pas;
		pas >>= 1;
	}

	fout = fopen("gfact.out", "w");
	fprintf(fout, "%d", r + 1);
	fclose(fout);

	return 0;
}