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

mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());

int rand(int l, int r){
    uniform_int_distribution<int> uid(l, r);
    return uid(rng);
}
int32_t main()
{
ios_base::sync_with_stdio(false);
    cin.tie(NULL);

int tt=1;

//cout<<(1LL<<31LL)<<endl;
//cin>>tt;
//int T=

while(tt--)
{
   
   int n,m;
   cin>>n>>m;
   for(int i=0;i<n;i++){
int x;
    cin>>x;
}
int l=rand(0,1);
if(l==0)
    cout<<0<<"\n";
else cout<<max(0LL,m-n)<<"\n";
}}

/*stolen stuff you should look for
    * int overflow, array bounds
    * special cases (n=1?)
    * do smth instead of nothing and stay organized
    * WRITE STUFF DOWN
    * DON'T GET STUCK ON ONE APPROACH
*/