#include <bits/stdc++.h>
using namespace std;
const int MAX_N = 1e4;
const int MOD = 1e6 + 7;
int v[MAX_N + 2], t[MAX_N + 2], dpCrt[MAX_N + 2], dpPrv[MAX_N + 2], ans[MAX_N + 1];
int main() {
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
int n;
cin >> n;
for (int i = 1; i <= n; i++)
cin >> v[i];
for (int i = 1; i <= n; i++)
t[i] = max(t[i - 1], v[i - 1]);
for (int j = 1; j <= n; j++)
dpPrv[j] = 1;
for (int i = n; i >= 1; i--) {
ans[i] = dpPrv[t[i]];
for (int j = 1; j <= n; j++)
dpCrt[j] = ((long long)dpPrv[j] * j + dpPrv[j + 1]) % MOD;
for (int j = 1; j <= n; j++)
dpPrv[j] = dpCrt[j];
}
int day = 1;
for (int i = 2; i <= n; i++)
day = (day + (long long)(v[i] - 1) * ans[i]) % MOD;
cout << day << "\n";
return 0;
}
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