#include <bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef vector<int> vi;
typedef vector<ll> vl;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;

typedef int _loop_int;
#define REP(i,n) for(_loop_int i=0;i<(_loop_int)(n);++i)
#define FOR(i,a,b) for(_loop_int i=(_loop_int)(a);i<(_loop_int)(b);++i)
#define FORR(i,a,b) for(_loop_int i=(_loop_int)(b)-1;i>=(_loop_int)(a);--i)

#define DEBUG(x) cout<<#x<<": "<<x<<endl
#define DEBUG_VEC(v) cout<<#v<<":";REP(i,v.size())cout<<" "<<v[i];cout<<endl
#define ALL(a) (a).begin(),(a).end()

#define CHMIN(a,b) a=min((a),(b))
#define CHMAX(a,b) a=max((a),(b))

// mod
const ll MOD = 1000000007ll;
#define FIX(a) ((a)%MOD+MOD)%MOD

// floating
typedef double Real;
const Real EPS = 1e-11;
#define EQ0(x) (abs(x)<EPS)
#define EQ(a,b) (abs(a-b)<EPS)
typedef complex<Real> P;

int n;
int m[1252];
int err[1252];

ll dp[1252][1252];
// dp[i][j] := rest i items, split into j array
// dp[i][j] = 0 if there is error in j items or i<j
// dp[i][j] = sum_k<=j {jPk * dp[i-j][k]}
ll perm[1252][1252];

int main(){
  scanf("%d",&n);
  REP(i,n)scanf("%d",m+i);
  REP(i,n)m[i]--;
  
  REP(n,1252){
    perm[n][0] = 1;
    FOR(k,1,n+1)perm[n][k] = perm[n-1][k-1]*n%MOD;
  }

  REP(i,n-1)err[i+1] = (int)(m[i]>m[i+1]);
  REP(i,n-1)err[i+1] += err[i];

  dp[0][0] = 1;
  FOR(i,1,n+1)FOR(j,1,n+1){
    if(i<j)continue;
    int head = n-i;
    int tail = n-i + j;
    // printf("[%d,%d) -> %d-%d : %d\n",head,tail,err[tail-1],err[head],err[tail-1]-err[head]);
    if(err[tail-1] - err[head] > 0)continue;
    REP(k,j+1){
      dp[i][j] += perm[j][k] * dp[i-j][k] % MOD;
    }
    dp[i][j] %= MOD;
  }
  // REP(i,n+1){
  //   REP(j,n+1)printf("%3lld",dp[i][j]);
  //   puts("");
  // }
  ll ans = 0;
  FOR(j,1,n+1)ans = (ans + dp[n][j]) % MOD;
  printf("%lld\n",ans);
  return 0;
}