#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
#define F first
#define S second
#define pb push_back
#define endl "\n"
#define all(x) x.begin(), x.end()
const int M = 10007;
const ll inf = 2e9;
const ll mod = 1e6 + 7;
const double pi = acos(-1);
const int dx[] = {0, -1, 0, 1}, dy[] = {1, 0, -1, 0};
const int block = 320;
ll n, a[M], dp[M][M], pref[M], ans = 1;
ll solve(int i, int team){
if(i < 1) return 0;
if(i == n) return 1;
ll &ret = dp[i][team];
if(ret != -1) return ret;
ret = 0;
for(int j = 1; j <= team + 1; ++j) ret = (ret + solve(i + 1, max(team, j))) % mod;
return ret;
}
int main(){
cin >> n;
for(int i = 1; i <= n; ++i) cin >> a[i], pref[i] = max(pref[i - 1], a[i]);
for(int i = 0; i <= n; ++i) for(int j = 0; j <= n; ++j) dp[i][j] = -1;
for(int i = 1; i <= n; ++i) for(ll j = 1; j < a[i]; ++j) ans = (ans + solve(i, max(pref[i - 1], j))) % mod;
cout << ans << endl;
return 0;
}
