#include <bits/stdc++.h>
using namespace std;
#define int long long
#define F first
#define S second
#define el endl
#define cout(x) for(auto v:x)cout<<v<<' '
#define cin(x) for(auto &v:x)cin>>v;
#define pb(x) push_back(x)
#define all(x) x.begin(),x.end()
int freq1[10001],freq2[10001];
void testcases(int h){
int n,m,d;cin>>n>>d>>m;
vector<int>v;
for(int i=0;i<m;i++){
int x;cin>>x;
freq1[x]++;
freq2[x]++;
v.push_back(x);
}
int l=1,r=1e5,ans;
while(l<=r){
int m=(l+r)/2;
int num=1,f=1;
for(int i=1;i<=n;i++){
int cur=m;
if(i>num+d){
f=0;
break;
}
while(cur && freq1[num]<=cur && num<=i){
cur-=freq1[num];
freq1[num]=0;
num++;
}
if(cur && num<=i){
freq1[num]=freq1[num]-cur;
cur=0;
}
}
if(f){
ans=m;
r=m-1;
}
else{
l=m+1;
}
for(int i=1;i<=n;i++){
freq1[i]=freq2[i];
}
}
cout<<ans<<el;
}
int32_t main()
{
int tc=1;
// cin>>tc;
for(int i=1;i<=tc;i++)testcases(i);
return 0;
}
