#include <bits/stdc++.h>
using namespace std;
int main()
{
long long int a;
cin>>a;
long long int b;cin>>b;
map<long long int,long long int>mp;
long long int arr[a];
for(int i=0;i<a;i++)
{
int ele; cin>>ele;
arr[i]=ele;
mp[ele]++;
}
long long int dif=0;int cnt=0;
for(int i=0;i<a;i++)
{
dif=b-arr[i];
if(dif==0){mp[arr[i]]--;cnt++;}
else if(mp[dif]>0)
{
cnt++;
mp[dif]-=1;
mp[arr[i]]--;
}
else dif=0;
}
cout<<cnt<<endl ;
}
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