#include <iostream>
#include <iomanip>
#include <vector>
#include <cmath>
#include <algorithm>
#include <set>
#include <queue>
#include <map>
#include <stack>
#include <bitset>
#include <string>
#include <cstring>
#include <iterator>
#include <random>
using namespace std;
typedef long long ll;
typedef pair<ll, ll> pll;
typedef long double ld;
const ll dim = 1e6+7;
//const ll mod = 1e9 + 7;
const ll inf = 1e18 + 77;
#define endl "\n"
#define fi first
#define pb push_back
#define se second
#define vll vector<ll>
ll n;
ll x;
/*ll check(ll val){
ll tp1
for(int i=1; i<=n; i++){
}
}*/
ll a[dim];
int main() {
cin>>n>>x;
for(int i=1; i<=n; i++){
cin>>a[i];
a[i]=a[i]%x;
}
sort(a+1, a+1+n);
ll mn1=0;
ll mn2=0;
ll ans=inf;
ll md=(a[n/2]);
ll md2=(a[(n+1)/2]);
for(int i=1; i<=n; i++){
mn1=max(mn1, min(abs(x-a[i]-md)%x, abs(a[i]-md)%x));
mn2=max(mn2, min(abs(x-a[i]-md2)%x, abs(a[i]-md2)%x));
}
cout<<min(mn1, mn2)<<endl;
return 0;
}
