#include<bits/stdc++.h> using namespace std; using Int = long long; template<typename T1,typename T2> inline void chmin(T1 &a,T2 b){if(a>b) a=b;} template<typename T1,typename T2> inline void chmax(T1 &a,T2 b){if(a<b) a=b;} template<typename T> void drop(const T &x){cout<<x<<endl;exit(0);} //INSERT ABOVE HERE signed main(){ Int n,k; cin>>n>>k; if(n<k) drop(-1); drop(k-1); return 0; }