#define _USE_MATH_DEFINES #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include using namespace std; typedef long long ll; typedef unsigned long long ull; typedef pair i_i; typedef pair ll_i; typedef pair d_i; typedef pair ll_ll; typedef pair d_d; typedef pair i_ll; struct edge { int u, v; ll w; }; double INF = DBL_MAX / 10; ll MOD = 1000000007; ll _MOD = 1000000009; double EPS = 1e-10; int main() { ll lb, ub; cin >> lb >> ub; ub++; if (ub - lb < 500000) { ll ma = 0, ans; for (ll x = lb; x < ub; x++) for (ll p = 2; p * p <= x; p++) if (x % p == 0) { if (p >= ma) { ma = p; ans = x; } break; } cout << ans << endl; return 0; } vector a(20000001, -1); for (int i = 2; i <= 20000000; i++) if (a[i] == -1) for (int j = i * 2; j <= 20000000; j += i) if (a[j] == -1) a[j] = i; vector ps; for (int x = 500; x <= 100000; x++) if (a[x]) ps.push_back(x); ll ans; for (ll p: ps) for (ll x = (lb + p - 1) / p * p; x < ub; x += p) if (a[x / p] >= p) ans = x; cout << ans << endl; }