#include #define endl "\n" using namespace std; #define ll long long #define ld long double #define rep(i,n) for(int i = 0; i < (int)(n); i++) #define repo(i,n) for(int i = 1; i < (int)(n); i++) #define pb push_back #define mp make_pair #define np next_permutation #define fi first #define se second #define all(x) (x).begin(),(x).end() #define uniq(v) v.erase(unique(v.begin(),v.end()),v.end()) #define lb(v,x) (lower_bound(v.begin(),v.end(),x)-v.begin()) #define ub(v,x) (upper_bound(v.begin(),v.end(),x)-v.begin()) using Pair = pair>; #define pq priority_queue, greater> const ll mod=1000000007; //const ll mod=998244353; const ld pi=acos(-1.0); const ll INF = 1LL<<61; templatebool chmax(T &a, const T &b) { if (abool chmin(T &a, const T &b) { if (b>n; vectorp(n); vectorq(n); vectorr(n); rep(i,n) cin>>p[i]; rep(i,n) cin>>q[i]; rep(i,n) r[i]=p[i]-q[i]; sort(all(r)); ll ans=0; rep(i,n) { p[i]-=r[n-1]; if((q[i]-p[i])%2) { cout << -1 << endl; return 0; } else ans+=(q[i]-p[i])/2; } if(ans!=r[n-1]) cout << -1 << endl; else cout << ans << endl; }