//qscqesze
#include <cstdio>
#include <cmath>
#include <cstring>
#include <ctime>
#include <iostream>
#include <algorithm>
#include <set>
#include <vector>
#include <sstream>
#include <queue>
#include <typeinfo>
#include <fstream>
#include <map>
#include <stack>
typedef long long ll;
using namespace std;
//freopen("D.in","r",stdin);
//freopen("D.out","w",stdout);
#define sspeed ios_base::sync_with_stdio(0);cin.tie(0)
#define test freopen("test.txt","r",stdin)  
#define maxn 2000001
#define mod 10007
#define eps 1e-9
int Num;
char CH[20];
const int inf=0x3f3f3f3f;
const ll infll = 0x3f3f3f3f3f3f3f3fLL;
inline ll read()
{
    ll x=0,f=1;char ch=getchar();
    while(ch<‘0‘||ch>‘9‘){if(ch==‘-‘)f=-1;ch=getchar();}
    while(ch>=‘0‘&&ch<=‘9‘){x=x*10+ch-‘0‘;ch=getchar();}
    return x*f;
}
inline void P(int x)
{
    Num=0;if(!x){putchar(‘0‘);puts("");return;}
    while(x>0)CH[++Num]=x%10,x/=10;
    while(Num)putchar(CH[Num--]+48);
    puts("");
}
//**************************************************************************************

ll a[maxn];

multiset<ll> S;
int main()
{
    //test;
    int n;
    ll p;
    while(cin>>n>>p)
    {
        S.clear();
        for(int i=0;i<n;i++)
        {
            a[i]=read();
            a[i]%=p;
            S.insert(a[i]);
        }
        ll ans=0;
        for(int i=0;i<n;i++)
        {
            S.erase(S.find(a[i]));
            multiset<ll>::iterator it=S.lower_bound(p-a[i]);
            it--;
            ans=max(ans,(a[i]+*it)%p);
            it=S.lower_bound(p*2-a[i]);
            it--;
            ans=max(ans,(a[i]+*it)%p);
            S.insert(a[i]);
        }
        cout<<ans<<endl;
    }
    
}