#include <bits/stdc++.h>
using namespace std;
using ll = long long;
const string FNAME = "jobschedule";
const int MAXN = 100002, MAXM = 1000000;
struct Job {
int numJob, deadline;
Job() {}
Job(int num, int d) {
numJob = num;
deadline = d;
}
};
struct cmp {
bool operator() (const Job &a, const Job &b) {
if (a.deadline == b.deadline) return a.numJob < b.numJob;
return a.deadline < b.deadline;
}
};
int dayJobs[MAXN], tempDay[MAXN];
int n, delays, m;
bool goodJob(int machineNum) {
priority_queue<Job, vector<Job>, cmp> q;
for (int i = 1; i <= n; ++i) {
q.push(Job(dayJobs[i], i + delays));
int remain = machineNum - q.top().numJob;
while (q.size() && remain >= 0) {
q.pop();
if (q.size()) remain -= q.top().numJob;
}
if (q.size() && remain < 0) {
Job j = q.top();
j.numJob = -remain;
q.pop();
q.push(j);
}
}
return q.empty();
}
int minMachine(int l, int r) {
if (l == r) return l;
int mid = (l + r) / 2;
if (goodJob(mid)) return minMachine(l, mid);
return minMachine(mid + 1, r);
}
int main() {
ios_base::sync_with_stdio(false);
cout.tie(NULL);
cin.tie(NULL);
// freopen((FNAME + ".in").c_str(), "r", stdin);
// freopen((FNAME + ".out").c_str(), "w", stdout);
cin >> n >> delays >> m;
for (int i = 0; i < m; ++i) {
int day;
cin >> day;
++dayJobs[day];
}
cout << minMachine(1, 1000000);
return 0;
}
