#include<bits/stdc++.h>
#include <cstdio>
#include <cstring>
#include <cmath>
#include <string>
#include <chrono>
#include <complex>
using namespace std;
#define ll long long
#define ld long double
#define ui unsigned int
#define ull unsigned ll
#define mp                   make_pair
#define eb                   emplace_back
#define pb                   push_back
#define pf                   push_front
#define popb                 pop_back
#define popf                 pop_front
#define hashmap              unordered_map
#define hashset              unordered_set
#define lb                   lower_bound
#define ub                   upper_bound
#define all(a)               (a).begin(), (a).end()
#define rall(a)              (a).rbegin(), (a).rend()
#define ff                   first
#define ss                   second
#define foi(n) for(ll i=0;i<n;i++)
#define foj(n) for(ll j=0;j<n;j++)
#define fok(n) for(ll k=0;k<n;k++)
#define forr(i,a,b) for(ll i=a;i<b;i++)
#define forrr(i,b,a) for(ll i=b;i>=a;i--)
#define forrrr(i,a,b,k) for(ll i=a;i<b;i=i+k)
#define graph          vector<vector<ll>>
#define sz(v) v.size()
typedef pair<int, int> pii;
typedef pair<ll, ll>   pll;
typedef vector<int>         vi;
typedef vector<ll>          vll;
typedef vector<string>      vs;
typedef vector<double>      vd;
typedef vector<pii>         vpii;
typedef vector<pll>         vpll;
typedef pair< ll, pll>      plll;
typedef vector<plll>      vplll;
typedef  vector<string> 	     vs;
typedef  vector<char>	         vc;
typedef  vector<bool>            vb;
typedef  map<string, int>         msi;
typedef  map<int, int>	         mii;
typedef  map<ll, ll>             mll;
typedef  map<ll, vll>             mvll;
typedef  map<char, ll>           mcl;
typedef map<pair<ll, ll>, ll>  mplll;
typedef  unordered_map<char, ll>           umcl;
typedef  unordered_map< ll, char>           umlc;
typedef  map<int, string>	     mis;
typedef  pair<string, int>       psi;
typedef  pair<string, string>    pss;
typedef priority_queue <ll> pq;
typedef priority_queue<pii, vector<pii>, greater<pii> > pqq;
typedef priority_queue<ll, vector<ll>, greater<ll>> prq;
const ll MOD = 1000000007;
const ll modx = 998244353;
void solve();
int main()
{
	ios_base::sync_with_stdio(false); cin.tie(NULL);

#ifndef ONLINE_JUDGE
	freopen("input1.txt", "r", stdin);
	freopen("error1.txt", "w", stderr);
	freopen("output1.txt", "w", stdout);
#endif
//	ll t ; cin >> t;
//	while (t--)
	{
		solve();
		cout << "\n";
	}

	cerr << "time taken : " << (float)clock() / CLOCKS_PER_SEC << " secs" << endl;
	return 0;
}
ll ceils(ll x, ll y) {
	return x / y + ((x % y) != 0);
}
ll gcd(ll a, ll b) {
	if (b == 0)
		return a;
	else
		return gcd(b, a % b);
}


ll lcm(ll a, ll b) {
	return a / gcd(a, b) * b;

}
ll powmod(ll x, ll y) {
	ll res = 1;
	for (ll i = 0; i < y; i++) {
		res = res * x % MOD;
	}
	return res;
}
bool isPrime(ll n)
{
	if (n <= 1)
		return false;
	if (n <= 3)
		return true;
	if (n % 2 == 0 || n % 3 == 0)
		return false;

	for (ll i = 5; i * i <= n; i = i + 6)
		if (n % i == 0 || n % (i + 2) == 0)
			return false;

	return true;
}
ll kadanesAlgo(vll a)
{
	ll n = a.size();

	ll currMax = 0;
	ll mx = INT_MIN;

	foi(n)
	{
		currMax += a[i];

		if (currMax <= a[i])
		{
			currMax = a[i];
		}

		mx = max(currMax, mx);
	}
	return mx;
}
ll n, q;
//vll a(100001, 0);
void solve() {
	/*	cin >> n >> q;
		foi(n) {
			ll x;
			cin >> x;
			a[x]++;
		}
		foi(q) {
			ll z;
			cin >> z;
		}*/
	ll m;
	cin >> n >> m;
	double g = m / 100.0;
	double h = g * n;
	cout << fixed << setprecision(12);
	cout << h;

}

#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;



  
    
 
} 