#pragma GCC optimize("Ofast")
// #pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")

#include <bits/stdc++.h>
#define SIZE 300005
#define MOD 1000000007LL
#define EPS 1e-10
#define INF 2147483647
#define LLINF 9223372036854775807LL
#define REP(i,n) for(int i=0;i<n;i++)
#define FOR(i,a,b) for(int i=a;i<=b;i++)
#define DOWN(i,b,a) for(int i=b;i>=a;i--)
#define SET(a,c) memset(a,c,sizeof a)
#define BIT(i,j) ((i)>>(j))&1
#define ALL(o) (o).begin(), (o).end()
#define ERASE(o) (o).erase(unique((o).begin(),(o).end()), (o).end())
#define SQ(x) ((x)*(x))
using namespace std;
typedef int_fast64_t ll;
typedef pair<ll,ll> Pll;
typedef pair<int, int> Pii;
typedef pair<double, double> Pdd;
typedef complex<double> dcomplex;
template<typename T> inline void priv(vector<T>a){REP(i,a.size()){cerr<<a[i]<<((i==a.size()-1)?"\n":" ");}}
inline void fastio(){cin.tie(nullptr); cout.tie(nullptr); ios::sync_with_stdio(false); cout << fixed << setprecision(15);}
ll gcd(ll a,ll b){ll c=max(a,b);ll d=min(a,b);return c==0||d==0?c:gcd(c%d,d);}
ll lcm(ll a,ll b){return a==0||b==0?0:a*b/gcd(a,b);}

template<int N, typename T, T M>
struct ModFact {
    T inv[N+1];
    T fact[N+1];
    T ifact[N+1];
    constexpr ModFact() : fact(), ifact() {
        fact[0] = 1;
        for (int i = 0; i < N; i++)
            fact[i+1] = (fact[i]*(i+1))%M;
        ifact[N] = power(fact[N], M-2);
        for (int i = N-1; i >= 0; i--)
            ifact[i] = (ifact[i+1]*(i+1))%M;
        for (int i = 0; i < N; i++)
            inv[i] = (fact[i]*ifact[i+1])%M;
    }
    constexpr T power(T a, T b) {
        T r = 1;
        while (b>0) {
            if((b&1)!=0) r = (r*a)%M;
            a = (a*a)%M;
            b >>= 1;
        }
        return r;
    }
    constexpr T comb(T n, T r) {
        return (((fact[n]*ifact[r])%M)*ifact[n-r])%M;
    }
};

const int cm = 1 << 17;
char cn[cm], * ci = cn + cm, ct;
inline char getcha() {
	if (ci - cn == cm) { fread_unlocked(cn, 1, cm, stdin); ci = cn; }
	return *ci++;
}

inline int getint() {
	int A = 0;
	if (ci - cn + 16 > cm) while ((ct = getcha()) >= '0') A = A * 10 + ct - '0';
	else while ((ct = *ci++) >= '0') A = A * 10 + ct - '0';
	return A;
}

ModFact<100000, ll, MOD> fact;

ll N;

int main() {
    ll N, ans = 0, prev, now;
    N = getint();
    prev = getint();
    ll a = 0;
    REP(i, N-1) {
        now = getint();
        // cin >> now;
        a = (a + fact.inv[i]) % MOD;
        ans += a * (now - prev) % MOD;
        prev = now;
    }
    printf("%lld\n", (ans * fact.fact[N-1])%MOD);
	return 0;
}
