#include <iostream>
#include <cstdio>
#include <string>
#include <string.h>
#include <queue>
#include <math.h>
#include <cmath>
#include <map>
#include <set>
#include <vector>
#include <algorithm>
#include <bitset>
#include <ctype.h>
#include <cassert>
#include <stack>
#include <fstream>
#include <unordered_map>
#include <ctime>

using namespace std;

#define snd second
#define fst first
#define mp make_pair
#define ll long long
#define ull unsigned long long
#define ld long double
#define pb push_back
#define left _left
#define right _right

const ld pi = 3.14159265359;

template < typename T > T abs(T x)
{
    return x > 0 ? x : -x;
}

template < typename T > T sqr(T x)
{
    return x * x;
}

const int maxn = 1000005;
const ll mod = 1000000007;

char s[maxn];
int sp = 0;

ll dp[205][205];

int nxt()
{
    while (s[sp] == ' ')
    {
        sp++;
    }

    if (s[sp] == '?')
    {
        sp++;
        return -1;
    }

    int res = 0;
    while (s[sp] != ' ')
    {
        res = res * 10 + s[sp] - '0';
        sp++;
    }

    return res;
}


ll fact[maxn], invFact[maxn];
ll inv[maxn];

ll C(ll n, ll k)
{
    if (k > n)
        return 0;
    return (fact[n] * invFact[k] % mod) * invFact[n - k] % mod;
}

ll F(ll n, ll order)
{
    n -= order - 1;
    if (n < 0)
        return 0;
    return (C(2 * n + order - 1, n) * inv[n + order] % mod) * order % mod;
}

ll get(ll currPos, ll prvPos, ll prvCoeff, ll prvOrder, ll order)
{
    ll res = 0;
    for (int i = 0; i < 205; i++)
    {
        res += F(currPos - (prvPos - i), order) * dp[prvOrder][i] % mod;
    }

    return (res % mod) * prvCoeff % mod;
}

int main()
{
    //gen();
    //freopen("a.in", "r", stdin);
    //srand(time(NULL));

    inv[0] = 1;
    inv[1] = 1;

    for (int i = 2; i < maxn; i++)
    {
        inv[i] = (mod - mod / i) * inv[mod % i] % mod;
    }

    fact[0] = invFact[0] = 1;

    for (int i = 1; i < maxn; i++)
    {
        fact[i] = (fact[i - 1] * i) % mod;
        invFact[i] = (invFact[i - 1] * inv[i]) % mod;
    }

    dp[1][0] = 1;
    dp[2][1] = 1;
    dp[2][0] = mod - 1;

    for (int i = 3; i < 205; i++)
    {
        for (int j = 0; j < 204; j++)
            dp[i][j + 1] = (mod + dp[i - 1][j] - dp[i - 2][j]) % mod;
    }


    int n;
    scanf("%d\n", &n);

    gets(s);
    s[strlen(s)] = ' ';

    if (nxt() > 0)
    {
        cout << 0 << endl;
        return 0;
    }

    if (n == 1)
    {
        cout << 1 << endl;
        return 0;
    }

    int g = nxt();
    if (g != -1 && g != 1)
    {
        cout << 0 << endl;
        return 0;
    }


    ll prvPos = 1, prvCoeff = 1, prvOrder = 1;


    for (int i = 2; i < n; i++)
    {
        int c = nxt();

        if (c == 0)
        {
            cout << 0 << endl;
            return 0;
        }

        if (c > 0)
        {
            ll res = get(i, prvPos, prvCoeff, prvOrder, c);

            prvPos = i;
            prvCoeff = res;
            prvOrder = c;
        }
    }

    cout << get(n, prvPos, prvCoeff, prvOrder, 1) << endl;

    return 0;
}