#include #include #include #include #include #include #include #include #include #include #include #include #include #include #include using namespace std; namespace { using Integer = long long; //__int128; template istream& operator >> (istream& is, vector& vec){for(T& val: vec) is >> val; return is;} template istream& operator , (istream& is, T& val){ return is >> val;} template ostream& operator << (ostream& os, const vector& vec){for(int i=0; i ostream& operator , (ostream& os, const T& val){ return os << " " << val;} template void print(const H& head){ cout << head; } template void print(const H& head, const T& ... tail){ cout << head << " "; print(tail...); } template void println(const T& ... values){ print(values...); cout << endl; } template void eprint(const H& head){ cerr << head; } template void eprint(const H& head, const T& ... tail){ cerr << head << " "; eprint(tail...); } template void eprintln(const T& ... values){ eprint(values...); cerr << endl; } string operator "" _s (const char* str, size_t size){ return move(string(str)); } constexpr Integer my_pow(Integer x, Integer k, Integer z=1){return k==0 ? z : k==1 ? z*x : (k&1) ? my_pow(x*x,k>>1,z*x) : my_pow(x*x,k>>1,z);} constexpr Integer my_pow_mod(Integer x, Integer k, Integer M, Integer z=1){return k==0 ? z%M : k==1 ? z*x%M : (k&1) ? my_pow_mod(x*x%M,k>>1,M,z*x%M) : my_pow_mod(x*x%M,k>>1,M,z);} constexpr unsigned long long operator "" _ten (unsigned long long value){ return my_pow(10,value); } inline int k_bit(Integer x, int k){return (x>>k)&1;} //0-indexed mt19937 mt(chrono::duration_cast(chrono::steady_clock::now().time_since_epoch()).count()); template string join(const vector& v, const string& sep){ stringstream ss; for(int i=0; i0) ss << sep; ss << v[i]; } return ss.str(); } } constexpr long long mod = 9_ten + 7; vector > prime_factorization(long long N){ vector< pair > ret; for(long long i=2; i*i<=N; i++){ long long tmp = 0; while(N%i==0){ tmp++; N/=i; } if(tmp>0){ ret.push_back( make_pair(i, tmp) ); } } if(N!=1){ ret.push_back( make_pair(N, 1) ); } return ret; } vector Eratosthenes(long long N){ vector v(N+1, true); v[0] = v[1] = false; long long sqN = sqrt(N); for(int i=2; i<=sqN; i++){ if(v[i] == false) continue; for(long long j=i*i; j<=N; j+=i){ v[j] = false; } } vector Prime; for(long long i=2; i<=N; i++){ if(v[i]==true) Prime.push_back(i); } return Prime; } int main(){ long long l,h; cin >> l,h; auto p = Eratosthenes(sqrt(h)+100); sort(p.begin(), p.end()); eprintln(p.size()); long long ans = -1; for(long long a : p){ if(h/a - (l-1)/a <= 0) continue; for(long long x=(h/a)*a; x>=l; x-=a){ if(x%a == 0){ bool unko=false; for(long long b : p){ if(b==a) break; if(x%b==0){ unko = true; break; } } if(!unko){ ans = x; //eprintln(ans, a); break; } } } } assert(ans != -1); println(ans); return 0; }