#include <bits/stdc++.h>

using namespace std;

#define REP(i, N) for (int i = 0; i < (int)N; i++)
#define FOR(i, a, b) for (int i = a; i < (int)b; i++)
#define ALL(x) (x).begin(), (x).end()
#define INF (1 << 30)
#define LLINF (1LL << 62)
#define DEBUG(...) debug(__LINE__, ":" __VA_ARGS__)

constexpr int MOD = 1000000007;
using ll = long long;
using Pii = pair<int, int>;
using Pll = pair<ll, ll>;

template <class T>
string to_string(T s);
template <class S, class T>
string to_string(pair<S, T> p);
string to_string(string s) { return s; }
string to_string(const char s[]) { return to_string(string(s)); }

template <class T>
string to_string(T v) {
  if (v.empty()) return "{}";
  string ret = "{";
  for (auto x : v) ret += to_string(x) + ",";
  ret.back() = '}';
  return ret;
}
template <class S, class T>
string to_string(pair<S, T> p) {
  return "{" + to_string(p.first) + "," + to_string(p.second) + "}";
}

void debug() { cerr << endl; }
template <class Head, class... Tail>
void debug(Head head, Tail... tail) {
  cerr << to_string(head) << " ";
  debug(tail...);
}

struct IO {
#ifdef _WIN32
  inline char getchar_unlocked() { return getchar(); }
  inline void putchar_unlocked(char c) { putchar(c); }
#endif
  string separator = " ";
  template <class T>
  inline void read(T& x) {
    char c;
    do {
      c = getchar_unlocked();
    } while (c != '-' && (c < '0' || '9' < c));
    bool minus = 0;
    if (c == '-') {
      minus = 1;
      c = getchar_unlocked();
    }
    x = 0;
    while ('0' <= c && c <= '9') {
      x *= 10;
      x += c - '0';
      c = getchar_unlocked();
    }
    if (minus) x = -x;
  }
  inline void read(string& x) {
    char c;
    do {
      c = getchar_unlocked();
    } while (c == ' ' || c == '\n');
    x.clear();
    do {
      x += c;
      c = getchar_unlocked();
    } while (c != ' ' && c != '\n' && c != EOF);
  }
  template <class T>
  inline void read(vector<T>& v) {
    for (auto& x : v) read(x);
  }
  template <class Head, class... Tail>
  inline void read(Head& head, Tail&... tail) {
    read(head);
    read(tail...);
  }
  template <class T>
  inline void write(T x) {
    char buf[32];
    int p = 0;
    if (x < 0) {
      x = -x;
      putchar_unlocked('-');
    }
    if (x == 0) putchar_unlocked('0');
    while (x > 0) {
      buf[p++] = (x % 10) + '0';
      x /= 10;
    }
    while (p) {
      putchar_unlocked(buf[--p]);
    }
  }
  inline void write(string x) {
    for (char c : x) putchar_unlocked(c);
  }
  inline void write(const char s[]) {
    for (int i = 0; s[i] != 0; ++i) putchar_unlocked(s[i]);
  }
  template <class T>
  inline void write(vector<T> v) {
    for (auto itr = v.begin(); itr + 1 != v.end(); ++itr) {
      write(*itr);
      write(separator);
    }
    write(v.back());
  }
  template <class Head, class... Tail>
  inline void write(Head head, Tail... tail) {
    write(head);
    write(separator);
    write(tail...);
  }
  template <class Head, class... Tail>
  inline void writeln(Head head, Tail... tail) {
    write(head, tail...);
    write("\n");
  }
  void set_separator(string s) { separator = s; }
} io;

int main() {
  int N;
  string S;
  io.read(N, S);
  using Pss = pair<string, string>;
  map<Pss, ll> left, right;
  ll ans = 0;
  REP(b, 1 << N) {
    string l_r, l_b, r_r, r_b;
    REP(i, N)
    if ((b >> i) & 1) {
      l_r += S[i];
      r_r += S[2 * N - 1 - i];
    } else {
      l_b += S[i];
      r_b += S[2 * N - 1 - i];
    }
    left[Pss(l_r, l_b)]++;
    right[Pss(r_r, r_b)]++;
  }
  for (auto l : left)
    ans += l.second * right[Pss(l.first.second, l.first.first)];
  io.writeln(ans);
  return 0;
}
#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <cassert>
#include <string>
#include <cstring>
#include <vector>
#include <list>
#include <map>
#include <set>
#include <stack>
#include <queue>
#include <algorithm>

using namespace std;

// ---------------------
// repetition
#define FOR(i,a,b) for(int i=(a);i<(b);++i)
#define REP(i,n) FOR(i,0,n)

// debug
#define dump(x)  cerr << #x << " = " << (x) << endl;
#define debug(x) cerr << #x << " = " << (x) << " (L" << __LINE__ << ")" << " " << __FILE__ << endl;

// ---------------------
#define INF 922337203685477580
typedef long long ll;

int main() {
  int n;
  cin >> n;

  int G[n][n];
  int visited[n];
  int d[n];
  int p[n];
  REP(y, n) {
    REP(x, n) {
      int cost;
      cin >> cost;

      if (cost == -1) {
        G[y][x] = 1 << 15;
      } else {
        G[y][x] = cost;
      }
    }
    visited[y] = 0;
    d[y] = 1 << 15;
    p[y] = -1;
  }

  d[0] = 0;

  REP(_, n) {
    int mincost = 1 << 15;
    int minv = -1;
    REP(v, n) {
      if (!visited[v] && d[v] < mincost) {
        minv = v;
        mincost = d[v];
      }
    }
    visited[minv] = 1;
    REP(to, n) {
      if (!visited[to] && G[minv][to] < (1 << 15) && G[minv][to] < d[to]) {
        d[to] = G[minv][to];
        p[to] = minv;
      }
    }
  }

  ll sum = 0;
  REP(i, n) {
    if (p[i] != -1) {
      sum += G[i][p[i]];
    }
  }

  cout << sum << endl;
  return 0;
}