#include <bits/stdc++.h> using namespace std; #define bismillah ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0); #define ll long long #define pll pair<ll, ll> #define fi first #define se second #define pb push_back #define endl '\n' ll N, T, a[500100]; void solve() { cin >> N >> T; for (int i = 0; i < N; i++) { cin >> a[i]; } sort(a, a+N); ll s = a[1]-a[0]; ll an = min(s%T, T - (s%T)); cout << (an/2 + an%2) << endl; } int main() { bismillah; int Tc = 1; // cin >> T; for (;Tc--;) solve(); }