#include <cassert>
#include <cmath>
#include <cstdint>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <algorithm>
#include <bitset>
#include <complex>
#include <deque>
#include <functional>
#include <iostream>
#include <limits>
#include <map>
#include <numeric>
#include <queue>
#include <random>
#include <set>
#include <sstream>
#include <string>
#include <unordered_map>
#include <unordered_set>
#include <utility>
#include <vector>

using namespace std;

using Int = long long;

template <class T1, class T2> ostream &operator<<(ostream &os, const pair<T1, T2> &a) { return os << "(" << a.first << ", " << a.second << ")"; };
template <class T> ostream &operator<<(ostream &os, const vector<T> &as) { const int sz = as.size(); os << "["; for (int i = 0; i < sz; ++i) { if (i >= 256) { os << ", ..."; break; } if (i > 0) { os << ", "; } os << as[i]; } return os << "]"; }
template <class T> void pv(T a, T b) { for (T i = a; i != b; ++i) cerr << *i << " "; cerr << endl; }
template <class T> bool chmin(T &t, const T &f) { if (t > f) { t = f; return true; } return false; }
template <class T> bool chmax(T &t, const T &f) { if (t < f) { t = f; return true; } return false; }
#define COLOR(s) ("\x1b[" s "m")


int N;
vector<int> P;

// dp[a][b][c][d]: index [a, b), value [c, d), max = d-1
Int dp[55][55][55][55];
Int DP[55][55][55][55];

int main() {
  for (; ~scanf("%d", &N); ) {
    P.resize(N);
    for (int i = 0; i < N; ++i) {
      scanf("%d", &P[i]);
      --P[i];
    }
    
    vector<int> invP(N, -1);
    for (int i = 0; i < N; ++i) invP[P[i]] = i;
    
    for (int a = N; a >= 0; --a) for (int b = a; b <= N; ++b) {
      for (int c = N; c >= 0; --c) for (int d = c; d <= N; ++d) {
        dp[a][b][c][d] = 0;
        DP[a][b][c][d] = 0;
      }
    }
    for (int a = N; a >= 0; --a) for (int b = a; b <= N; ++b) {
      for (int c = N; c >= 0; --c) for (int d = c; d <= N; ++d) {
        if (c == d) {
          dp[a][b][c][d] = 1;
          DP[a][b][c][d] = 1;
        } else {
          const int i = invP[d - 1];
          if (a <= i && i < b) {
            // (max of [a, i)) = p-1
            for (int p = c; p <= d - 1; ++p) {
              dp[a][b][c][d] += dp[a][i][c][p] * DP[i + 1][b][p][d - 1];
            }
          }
          DP[a][b][c][d] = DP[a][b][c][d - 1] + dp[a][b][c][d];
        }
      }
    }
    const Int ans = DP[0][N][0][N] - 1;
    printf("%lld\n", ans);
  }
  return 0;
}