#include <bits/stdc++.h>
#define L(i,j,k) for(int i=(j);i<=(k);i++)
#define R(i,j,k) for(int i=(j);i>=(k);i--)
#define all(x) x.begin(),x.end()
#define sz(a) ((int)a.size())
#define pb push_back
using namespace std;
typedef long long ll;
int main(){
ll n,t;cin>>n>>t;
vector<ll>a(n);
L(i,0,n-1)cin>>a[i];
vector<ll>md(n);
L(i,0,n-1){
md[i]=a[i]%t;
}
ll r1=max_element(all(md))-begin(md);
ll l1=min_element(all(md))-begin(md);
ll cut=max(1ll,(t+1)/2);
L(i,0,n-1){
if(md[i]>cut){
md[i]=t-md[i];
}
}
int r=max_element(all(md))-begin(md);
int l=min_element(all(md))-begin(md);
cout<<min(md[r]-md[l],md[r1]-md[l1])<<endl;
}
