#pragma GCC optimize("Ofast") #include #define rep(i,n) for(int i=0;i>x[i]; #define ft first #define sc second #define pb push_back #define lb lower_bound #define ub upper_bound #define all(v) (v).begin(),(v).end() #define LB(a,x) lb(all(a),x)-a.begin() #define UB(a,x) ub(all(a),x)-a.begin() #define mod 1000000007 //#define mod 998244353 #define FS fixed< using V=vector; using Graph = vector>; using P=pair; typedef unsigned long long ull; typedef long double ldouble; template inline bool chmin(T& a, T b) { if (a > b) { a = b; return true; } return false; } template inline bool chmax(T& a, T b) { if (a < b) { a = b; return true; } return false; } template inline void out(T a){ cout << a << '\n'; } void YN(bool ok){if(ok) cout << "Yes" << endl; else cout << "No" << endl;} //void YN(bool ok){if(ok) cout << "YES" << endl; else cout << "NO" << endl;} const ll INF=1e18; const int mx=200005; bool dp[1000001]; int main(){ cin.tie(0);ios::sync_with_stdio(false); ll a,b; cin>>a>>b; if(__gcd(a,b)!=1) cout<<-1<