/**
 * @author /u/Philboyd_Studge on 12/19/2015.
 */
public class Advent20 {

    public static void main(String[] args) {

        final int TARGET = 36000000;
        final int MAX = 1000000;
        int[] houses = new int[MAX];
        int answer = 0;

        boolean part1 = true;

        for (int elf = 1; elf < MAX; elf++) {
            if (part1) {
                for (int visited = elf; visited < MAX; visited += elf) {
                    houses[visited] += elf * 10;
                }
            } else {
                for (int visit = elf; (visit <= elf*50 && visit < MAX); visit += elf) {
                    houses[visit] += elf * 11;
                }
            }
        }

        for (int i = 0; i < MAX; i++) {
            if (houses[i] >= TARGET) {
                answer = i;
                break;
            }
        }

        System.out.println(answer);
    }
}