#include <bits/stdc++.h>
using namespace std;
typedef pair<int,int> ii;
typedef long long ll;
#define fs first
#define sc second

const int N = 1204;
const ll mod = 1000000007; 
ll cc, dp[N][N], M[N];

int main(){
	ll n;
	cin >> n;
	dp[n][0] = 1;
	for(ll i = 0; i < n; ++i) cin >> M[i];
	for(ll i = n - 1; i >= 0; --i){
		cc = M[i] > M[i + 1] ? 1 : cc + 1;
		for(ll j = 1; j <= cc; ++j){
			ll p = 1;
			for(ll k = 0; k <= j; ++k){
				(dp[i][j] += p * dp[i + j][k]) %= mod;
				(p *= j - k) %= mod; 
			}
		}
	}
	ll ans = 0;
	for(ll i = 1; i <= n; ++i) (ans += dp[0][i]) %= mod;
	cout << ans;
}