#include <bits/stdc++.h> using namespace std; #define fastio ios::sync_with_stdio(false); cin.tie(nullptr); #define s(x) x.size() #define sort(x) sort(x.begin(),x.end()) #define rsort(x) sort(x.rbegin(),x.rend()) #define all(x) (x).begin(), (x).end() #define pb push_back #define fi first #define se second #define INF 1e9 #define INFL 1e18 using ll = long long; using pii = pair<ll, ll>; vector<ll>v; ll t; ll how_much(ll sr){ ll n = v.size(); ll s = 0; for (ll i = 0; i < n; i++) { s=max(s,min(abs(v[i]-sr)%t,abs(t-abs(v[i]-sr)%t))); } return s; } void solve() { ll n; cin >> n >> t; v.resize(n); for (ll i = 0; i < n; i++) { cin >> v[i]; } ll l=0,r=1e9; // ll poprzedni = how_much((l+r+1)/2+1); ll essa = how_much(0); for (ll i = 1; i <= t; i++) { ll sigma = how_much(i); // if(sigma>=essa){ // cout << essa << endl; // return ; // } essa=min(essa,sigma); } cout << essa << endl; // cout << endl; // while(l<r){ // int sr = (l+r)/2; // ll wynik = how_much(sr); // if(wynik<=poprzedni) r = sr; // else l = sr+1; // } // cout << how_much(l) << endl; } int main() { fastio; int t = 1; // cin >> t; while (t--) solve(); return 0; }