#include <bits/stdc++.h>
using namespace std;
int main(){
  int N; cin>>N;
  vector<long long>A(N-1,0), B(N-1,0), C(N,0);
  long long a=1, z=1e9+7;
  for(int i=1; i<N; i++){
    a*=i, a%=z, A[i-1]=a;
  }
  a=1;
  for(int i=N-1; i>0; i--){
    a*=i, a%=z, B[(N-1)-i]=a;
  }
  for(int i=0; i<N; i++){
    cin>>a;
    C[i]=a;
  }
  long long ans=0;
  for(int i=0; i<N-1; i++){
    if(i==0) ans+=((C[N-1]-C[i])*B[N-3-i])%z, ans%=z;
    else if(i==N-2) ans+=((C[N-1]-C[i])*A[i-1])%z, ans%=z;
    else ans+=((C[N-1]-C[i])*((A[i-1]*B[N-3-i])%z))%z, ans%=z;
  }
  cout<<ans<<endl;
}
