#include // cout, endl, cin #include // string, to_string, stoi #include // vector #include // min, max, swap, sort, reverse, lower_bound, upper_bound #include // pair, make_pair #include // tuple, make_tuple #include // int64_t, int*_t #include // printf #include // map #include // queue, priority_queue #include // set #include // stack #include // deque #include // unordered_map #include // unordered_set #include // bitset #include // isupper, islower, isdigit, toupper, tolower #include // setprecision #include // complex #include #define enld '\n' #define rep(i,n) for(int i=0; i<(n); i++) using namespace std; using ll = long long; using P = pair; #pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native") #pragma GCC optimize("Ofast") constexpr ll INF = 1e18; constexpr int inf = 1e9; constexpr ll mod = 1000000007; constexpr ll mod2 = 998244353; const double PI = 3.1415926535897932384626433832795028841971; const int dx[8] = {1, 0, -1, 0,1,1,-1,-1}; const int dy[8] = {0, 1, 0, -1,1,-1,1,-1}; template inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1; } return 0; } template inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1; } return 0; } // --------------------------------------------------------------------------- int main(){ ios::sync_with_stdio(false); cin.tie(nullptr); int N; cin >> N; vector A(N); ll sum_A = 0; for(int i=0; i> A[i]; sum_A += A[i]; } vector B(N); ll sum_B = 0; for(int i=0; i> B[i]; sum_B += B[i]; } if((sum_A-sum_B)%(N-2) != 0){ cout << "-1\n"; return 0; } ll cnt = (sum_A-sum_B)/(N-2); ll now = 0; for(int i=0; i B[i] || (B[i]-A[i])%2){ cout << -1 << "\n"; return 0; } now += (B[i]-A[i])/2; } if(now == cnt){ cout << now << "\n"; }else{ cout << -1 << "\n"; } return 0; }