#include <bits/stdc++.h>

using namespace std;
typedef long long ll;
typedef pair<int,int> P;

ll modpow(ll a, ll p, ll mod){
        if(p == 0) return 1;
        if(p%2 == 0){
            ll half = modpow(a, p/2,mod);
            return half * half % mod;
        }
        else return a * modpow(a,p-1,mod) % mod;
    }

int main() {
    cin.tie(0);
    ios::sync_with_stdio(false);

    ll N; cin >> N;
    ll x[100005];
    for (int i = 0;i < N;i++){
        cin >> x[i];
    }

    ll mod = 1e9+7;
    ll ans = 0;

    ll tmp = 1;
    for (ll i = 1;i < N;i++){
        tmp = (tmp*i)%mod;
    }

    ll dif = tmp*modpow(2,mod-2,mod)%mod;

    ll cnt = 2;
    for (ll i = 0;i < N-1;i++){
        //cout << tmp << endl;
        ans += (x[i+1]-x[i])*tmp;
        ans %= mod;
        tmp = (tmp+dif) % mod;
        dif = ((dif*cnt)%mod)*modpow(cnt+1,mod-2, mod)%mod; 
        cnt++;
    }

    cout << ans << endl;

    return 0;

}