#include <bits/stdc++.h>
using namespace std;
using lint = long long;
const lint mod = 1e9 + 7;
#define all(x) (x).begin(), (x).end()
#define bitcount(n) __builtin_popcountl((lint)(n))
#define fcout cout << fixed << setprecision(15)
#define highest(x) (63 - __builtin_clzl(x))
template<class T> inline void YES(T condition){ if(condition) cout << "YES" << endl; else cout << "NO" << endl; }
template<class T> inline void Yes(T condition){ if(condition) cout << "Yes" << endl; else cout << "No" << endl; }
template<class T = string, class U = char>int character_count(T text, U character){ int ans = 0; for(U i: text){ ans += (i == character); } return ans; }
lint power(lint base, lint exponent, lint module){ if(exponent % 2){ return power(base, exponent - 1, module) * base % module; }else if(exponent){ lint root_ans = power(base, exponent / 2, module); return root_ans * root_ans % module; }else{ return 1; }}
struct position{ int y, x; }; position mv[4] = {{0, -1}, {1, 0}, {0, 1}, {-1, 0}}; // double euclidean(position first, position second){ return sqrt((second.x - first.x) * (second.x - first.x) + (second.y - first.y) * (second.y - first.y)); }
template<class T, class U> string to_string(pair<T, U> x){ return to_string(x.first) + "," + to_string(x.second); } string to_string(string x){ return x; }
template<class itr> void array_output(itr start, itr goal){ string ans; for(auto i = start; i != goal; i++) ans += to_string(*i) + " "; if(!ans.empty()) ans.pop_back(); cout << ans << endl; }
template<class itr> void cins(itr first, itr last){ for(auto i = first; i != last; i++){ cin >> (*i); } }
template<class T> T gcd(T a, T b){ if(a && b){ return gcd(min(a, b), max(a, b) % min(a, b)); }else{ return a; }} template<class T> T lcm(T a, T b){ return a / gcd(a, b) * b; }
struct combination{ vector<lint> fact, inv; combination(int sz) : fact(sz + 1), inv(sz + 1){ fact[0] = 1; for(int i = 1; i <= sz; i++){ fact[i] = fact[i - 1] * i % mod; } inv[sz] = power(fact[sz], mod - 2, mod); for(int i = sz - 1; i >= 0; i--){ inv[i] = inv[i + 1] * (i + 1) % mod; } } lint P(int n, int r){ if(r < 0 || n < r) return 0; return (fact[n] * inv[n - r] % mod); } lint C(int p, int q){ if(q < 0 || p < q) return 0; return (fact[p] * inv[q] % mod * inv[p - q] % mod); } };
template<class itr> bool next_sequence(itr first, itr last, int max_bound){ itr now = last; while(now != first){ now--; (*now)++; if((*now) == max_bound){ (*now) = 0; }else{ return true; } } return false; }
template<class itr, class itr2> bool next_sequence2(itr first, itr last, itr2 first2, itr2 last2){ itr now = last; itr2 now2 = last2; while(now != first){ now--, now2--; (*now)++; if((*now) == (*now2)){ (*now) = 0; }else{ return true; } } return false; }

combination table(1e6);

int main(){
    lint N;
    cin >> N;
    lint x[N];
    cins(x, x + N);
    lint sum[N + 1];
    sum[0] = 0;
    for(int i = 0; i < N; i++){
        sum[i + 1] = (sum[i] + x[i]) % mod;
    }
    lint ans = 0;
    for(lint k = 1; k < N - 1; k++){
        lint add = table.fact[N - 1] * ((k * k - 2 * k * N + k + (N - 1) * N + mod * lint(1e9)) % mod) % mod * table.inv[N - k] % mod * table.fact[N - k - 2] % mod;
        add = (add * power((k * (k + 1)) % mod, mod - 2, mod)) % mod;
        ans += add * (sum[N - 1] - sum[k]) % mod;
        ans += add * (mod - sum[N - k - 1]) % mod;
    }
    for(lint i = 0; i < N - 1; i++){
        lint k = N - 1 - i;
        lint p = (x[N - 1] - x[i]) * table.fact[i] % mod;
        ans += p * table.fact[N - 1] % mod * (N - k) % mod * table.inv[N - k] % mod * power(k, mod - 2, mod) % mod;
        ans %= mod;
    }
    
    /*
    for(int k = 1; k < N - 1; k++){
        for(int i = 0; i + k < N - 1; i++){
            lint p = (x[i + k] - x[i]) * table.fact[N - k - 2] % mod;
            for(int j = 1; j <= N - 1; j++){
                ans += p * table.P(j - 1, k - 1) % mod * (N - j - 1) % mod;
            }
        }
    }
    
    for(int i = 0; i < N - 1; i++){
        int k = int(N) - 1 - i;
        lint p = (x[N - 1] - x[i]) * table.fact[i] % mod;
        for(int j = 1; j <= N - 1; j++){
            ans += p * table.P(j - 1, k - 1) % mod;
        }
    }
     */
    cout << ans % mod << endl;
    
    /*
    for(int i = 0; i < N - 1; i++){
        for(int j = 1; j <= N - 1; j++){
            for(int k = 1; i + k < N - 1; k++){
                //cout << i + 1 << " when " << j << " " << p << endl;
                ans += (x[i + k] - x[i]) * (N - j - 1) % mod * power(N - k - 1, mod - 2, mod) % mod * table.P(j - 1, k - 1) % mod * power(table.P(N - 2, k - 1), mod - 2, mod) % mod;
            }
            ans += (x[N - 1] - x[i]) * table.P(j - 1, N - i - 2) % mod * power(table.P(N - 2, N - i - 2), mod - 2, mod) % mod;
        }
    }
    
    cout << ans * table.fact[N - 2] % mod << endl;*/
}



Measured memory_bytes: 19328