#include <iostream>#include <cstdlib>#include <cstring>#include <cstdio>using namespace std;int s, e;int count_two, count_five;int get_digit(int s, int e){ int s1 = s / 10 * 10 + 10; int e1 = e / 10 * 10; int ret = 1; if (e1 <= s1) { for (int i = s; i <= e; i++) if ((i & 1) && (i % 5 != 0)) ret = ret * (i % 10) % 10; return ret; } ret = (e1 - s1) / 10 % 2 * 8 + 1; for (int i = s; i < s1; i++) if ((i & 1) && (i % 5 != 0)) ret = ret * (i % 10) % 10; for (int i = e1 + 1; i <= e; i++) if ((i & 1) && (i % 5 != 0)) ret = ret * (i % 10) % 10; return ret;}int cal_odd(int s, int e){ if (s > e) return 1; int ret = get_digit(s, e); int s1 = s; while (s1 % 10 != 5) s1++; int e1 = e; while (e1 > 0 && e1 % 10 != 5) e1--; if (e1 < s1) return ret; s1 /= 5; e1 /= 5; ret = ret * cal_odd(s1, e1) % 10; count_five += (e1 - s1) / 2 + 1; return ret;}int cal(int s, int e){ if (s > e) return 1; int ret = cal((s + 1) / 2, e / 2) % 10; count_two += e / 2 - (s + 1) / 2 + 1; ret = ret * cal_odd(s, e) % 10; return ret;}void test(int s, int e){ long long a = 1; for (int i = s; i <= e; i++) { a *= i; while (a % 10 == 0) a /= 10; } printf("%lld", a % 10);}int main(){ while (~scanf("%d%d", &e, &s)) { s = e - s + 1; count_two = 0; count_five = 0; int ans = cal(s, e); if (count_five > count_two) { puts("5"); continue; } int temp = count_two - count_five; if (temp == 0) { printf("%dn", ans); continue; } temp--; ans = ans * 2 % 10; for (int i = 0; i < temp % 4; i++) ans = ans * 2 % 10; printf("%dn", ans); } return 0;}
