#include <bits/stdc++.h>
#pragma GCC optimize("-Ofast")
//#pragma GCC optimize("trapv")
#pragma GCC target("sse,sse2,sse3,ssse3,sse4,sse4.2,popcnt,abm,mmx,avx2,tune=native")
#pragma GCC optimize("-ffast-math")
#pragma GCC optimize("-funroll-loops")
#define I inline void
#define S struct
#define vi vector<int>
#define vii vector<pair<int, int>>
#define pii pair<int, int>
#define pll pair<ll, ll>
using namespace std;
using ll = long long;
using ld = long double;
const int N = 10000 + 7, mod = 1e6 + 7;
const ll inf = 2e18;
// How interesting!
int n;
int a[N], b[N];
int Max;
int c[N][N];
int mul(int x, int y) { return 1ll * x * y % mod; }
int add(int x, int y) { return (x + y) >= mod ? x + y - mod : x + y; }
int dp[N], ndp[N];
void dodp()
{
for (int i = 0; i <= n; ++i)
{
ndp[i] = add(dp[i + 1], mul(i, dp[i]));
}
for (int i = 0; i <= n; ++i)
{
dp[i] = ndp[i];
}
}
int main()
{
ios_base::sync_with_stdio(0);
cin.tie(0);
//freopen("in.in", "r", stdin);
cin >> n;
for (int i = 0; i < n; ++i)
dp[i] = 1;
for (int i = 0; i < n; ++i)
{
cin >> a[i];
if (i)
b[i] = max(b[i - 1], a[i]);
else
b[i] = a[i];
}
int ans = 0;
for (int i = n - 1; ~i; --i)
{
int x = a[i];
for (int j = 1; j < x; ++j)
{
int k = (i ? b[i - 1] : 0);
ans = add(ans, dp[max(j, i ? b[i - 1] : 0)]);
}
Max = max(Max, x);
dodp();
}
cout << add(ans, 1);
return 0;
}
/*
- bounds sir (segtree = 4N, eulerTour = 2N, ...)
- a variable defined twice?
- will overflow?
- is it a good complexity?
- don't mess up indices (0-indexed vs 1-indexed)
- reset everything between testcases.
*/
