#include <bits/stdc++.h>
using namespace std;

#define rep(i, from, to) for (int i = from; i < (to); ++i)
#define trav(a, x) for (auto& a : x)
#define all(x) x.begin(), x.end()
#define sz(x) (int)(x).size()
typedef long long ll;
typedef pair<int, int> pii;
typedef vector<int> vi;

const ll mod = 1000000007;

int N;
vi val;
vector<vector<ll>> mem;
vector<vector<ll>> bin;
vector<ll> fact;
ll solve(int at, int arsize) {
	if (at == N) return 1;
	ll& out = mem[at][arsize];
	if (out != -1) return out;
	ll res = 0;
	rep(i,at+1,N+1) {
		if (i-1 > at && val[i-1] < val[i-2]) break;
		int len = i - at;
		if (len > arsize) break;
		if (at == 0 && i != arsize) continue;
		ll v = bin[arsize][i - at] * solve(i, i - at) % mod;
		if (at != 0) {
			v = v * fact[i - at] % mod;
		}
		res += v;
	}
	res %= mod;
	out = res;
	return res;
}

int main() {
	cin.sync_with_stdio(false);
	cin.exceptions(cin.failbit);
	cin >> N;
	mem.assign(N, vector<ll>(N+1, -1));
	bin.assign(N+1, vector<ll>(N+1, 0));
	fact.assign(N+1, 1);
	bin[0][0] = 1;
	rep(i,1,N+1) fact[i] = fact[i-1] * i % mod;
	rep(n,1,N+1) {
		rep(k,0,n+1) {
			bin[n][k] = ((k == 0 ? 0 : bin[n-1][k-1]) + bin[n-1][k]) % mod;
		}
	}

	val.resize(N);
	vi seen(N);
	rep(i,0,N) {
		cin >> val[i];
		--val[i];
		if (seen[val[i]]++) {
			assert(0);
			return 0;
		}
	}
	ll res = 0;
	rep(i,1,N+1)
		res += solve(0, i);
	res %= mod;
	cout << res << endl;
}