/*
                    author         : TAPAN SAVANI 
                    codeforces     : savanitapan2001
                    codechef       : savanitapan17
*/

/*
------------------------------------------------------------------------

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------------------------------------------------------------------------
*/

#include <bits/stdc++.h>
using namespace std;

#define HAPPY_CODING              \
    ios_base::sync_with_stdio(0); \
    cin.tie(NULL);                \
    cout.tie(NULL);
#define pb push_back
#define mp make_pair
#define Debug(x) cout << #x " = " << (x) << endl
#define SORT(a) sort(a.begin(), a.end())
#define SORTR(a) sort(a.rbegin(), a.rend())
#define mod 1000000007
#define pi 3.141592653589793238
#define ll long long int
#define ull unsigned long long
#define be begin()
#define en end()
#define FOR(i, a, b) for (long long int i = a; i < b; i++)
#define FORI(i, a, b) for (int i = a; i >= b; i--)

typedef vector<int> VI;
typedef vector<ll> VL;
typedef pair<int, int> PI;
typedef pair<ll, ll> PL;
typedef vector<PI> VPI;

int main()
{
    HAPPY_CODING;

    int A, B;
    cin >> A >> B;
    for (int c = B;; c--)
        if ((A + c - 1) / c < B / c)
        {
            cout << c << endl;
            return 0;
        }
}


#include <bits/stdc++.h>
using namespace std;
#include <ext/pb_ds/assoc_container.hpp>
using namespace __gnu_pbds;
template <class c, class cmp = less<c> > using ordered_set = tree<c, null_type, cmp, rb_tree_tag, tree_order_statistics_node_update>;
#define IOS ios_base::sync_with_stdio(false);cin.tie(NULL);cout.tie(NULL);
#define TRACE
#ifdef TRACE
#define trace(...) __f(#__VA_ARGS__, __VA_ARGS__)
template <typename Arg1>
void __f(const char* name, Arg1&& arg1){
  cerr << name << " : " << arg1 << std::endl;
}
template <typename Arg1, typename... Args>
void __f(const char* names, Arg1&& arg1, Args&&... args){
  const char* comma = strchr(names + 1, ',');cerr.write(names, comma - names) << " : " << arg1<<" | ";__f(comma+1, args...);
}
#else
#define trace(...) 
#endif
template<class T> ostream& operator<<(ostream &os, vector<T> V) {os << "[ "; for(auto v : V) os << v << " "; return os << "]";}
template<class L, class R> ostream& operator<<(ostream &os, pair<L,R> P) {return os << "(" << P.first << "," << P.second << ")";}
template <typename T,typename U>pair<T,U> operator+(const pair<T,U> & l,const std::pair<T,U> & r) { return {l.first+r.first,l.second+r.second};}
typedef long long int ll;
const ll mod = 1e9 + 7;
const ll maxn = 5e6 + 5;
#define endl '\n'
#define ld long double
#define int ll
#define all(x)  (x).begin(),(x).end()
const ll md = (ll) 1e9 + 7;
 
inline ll add(ll a, ll b) {
  a += b;
  if (a >= md) a -= md;
  return a;
}
 
inline ll sub(ll a, ll b) {
  a -= b;
  if (a < 0) a += md;
  return a;
}
 
inline ll mul(ll a, ll b) {
  return (ll) ((long long)((a%md) * (b%md)) % md);
}
 
inline ll power(ll a, long long b) {
  ll res = 1;
  while (b > 0) {
    if (b & 1) {
      res = mul(res, a);
    }
    a = mul(a, a);
    b >>= 1;
  }
  return res;
}
 
inline ll inv(ll a) {
  a %= md;
  if (a < 0) a += md;
  ll b = md, u = 0, v = 1;
  while (a) {
    ll t = b / a;
    b -= t * a; swap(a, b);
    u -= t * v; swap(u, v);
  }
  assert(b == 1);
  if (u < 0) u += md;
  return u;
}

vector<int> fact(maxn+5);
void init (int n)
{
  fact[0] = 1;
  for(int i = 1;i<=n;i++)
  {
    fact[i] = mul(i,fact[i-1]);
  }
}
int nck(int n,int k)
{
  return mul(fact[n],mul(inv(fact[k]),inv(fact[n-k])));
}


int32_t main(){

  IOS

  init(5000000);

  int n, m;
  cin >> n >> m;
  vector<int> a(n);
  int k = 1;
  for(int i = 0;i<n;i++){
    cin >> a[i];
    m -= a[i];
    k += a[i] + 1;
  }

  if(m < 0){
    cout << 0 << endl;
    return 0;
  }

  int num = k - 1 + m;
  int den = k - 1;
  int ans = 1;
  for(int i = 0;i<den;i++){
    ans = mul(ans, num - i);
  }

  ans = mul(ans, inv(fact[den]));

  cout << ans << endl;



  
    
 
} 