#include <cstdio>
#include <cctype>

template <typename T> T read() {
  T res = 0, f = 1;
  char ch = getchar();
  for (; !isdigit(ch); ch = getchar()) if (ch == '-') f = -1;
  for (; isdigit(ch); ch = getchar()) res = (res << 3) + (res << 1) + (ch ^ 48);
  return res * f;
}

template <typename T> void read(T& x) {
  x = read<T>();
}

template <typename T, typename ...Others> void read(T& x, Others& ...y) {
  read(x);
  read(y...);
}

void read(char* x) {
  char ch = getchar();
  for (; isspace(ch); ch = getchar());
  for (; !isspace(ch); ch = getchar()) *x++ = ch;
  *x = 0;
}

void write(__int128 x) {
  if (x < 0) x = -x, putchar('-');
  int sta[64], top = 0;
  do {
    sta[++top] = x % 10;
    x /= 10;
  } while (x);
  while (top) {
    putchar(sta[top--] ^ 48);
  }
}

template <typename T> void write(T x) {
  write((__int128)x);
}

void write(char x) {
  putchar(x);
}

void write(char* x) {
  while (*x) putchar(*x++);
}

void write(const char* x) {
  while (*x) putchar(*x++);
}

template <typename T, typename ...Others> void write(T x, Others ...y) {
  write(x);
  write(y...);
}

const int MAXN = 1010;

int n;
int a[MAXN][MAXN], b[MAXN], c[MAXN];
int ans;

void check() {
  for (int i = 1; i <= n; ++i) {
    for (int j = 1; j <= n ; ++j) {
      if (a[i][j] != b[i] && a[i][j] != c[j]) return ;
    }
  }
  ans++;
  if (ans == 1000000007) ans = 0;
}

void generate_a(int nowx, int nowy) {
  if (nowy > n) {
    nowx++;
    nowy = 1;
  }
  if (nowx > n) {
    check();
    return ;
  }
  a[nowx][nowy] = 1;
  generate_a(nowx, nowy + 1);
  a[nowx][nowy] = 0;
  generate_a(nowx, nowy + 1);
}

void generate_c(int now) {
  if (now > n) {
    generate_a(1, 1);
    return ;
  }
  c[now] = 1;
  generate_c(now + 1);
  c[now] = 0;
  generate_c(now + 1);
}

int main() {
  freopen("01.in", "r", stdin);
  freopen("01.out", "w", stdout);
  read(n);
  for (int i = 1; i <= n ; ++i) {
    read(b[i]);
  }
  generate_c(1);
  write(ans, '\n');
  return 0;
}