#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
#define l(a, b, i) for (ll i = a; i < b; i++)
#define rl(a, b, i) for (ll i = a; i >= b; i--)
#define vpair vector<pair<ll, ll>>
#define inf LLONG_MAX
#define ninf LLONG_MIN
int main() {
ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
ll N, T; cin >> N >> T; vector<ll> vec(N);
l(0, N, i) cin >> vec[i];
sort(vec.begin(), vec.end());
ll div2 = T / 2;
if (T % 2 == 1) div2++;
set<ll> st;
l(0, N, i) {
ll re = vec[i] % T;
if (re >= div2) re = T - re;
st.insert(re);
}
ll sz = st.size();
ll sum = 0;
for (auto i : st) sum += i;
ll ans = sum / sz;
if (sum % sz > 0) ans++;
cout << ans;
}
