#include <iostream>
#include <fstream>
#include <algorithm>
using namespace std;
ifstream in("zombie.in");
ofstream out("zombie.out");
#define max(a,b)(a>b?a:b)
#define min(a,b)(a<b?a:b)
long long d,n,k,f,m,x,s;
int main()
{
in>>d>>n>>k;
while(n--){
    in>>x;
    if(m==0)f=x,m=1;
    else if(x-f>=d)
        if(m>=k)
            s+=k,f=x,m=1;
            else s+=m,f=x,m=1;
        else m++;
}
if(m>=k)
    s+=k,f=x,m=1;
    else s+=m,f=x,m=1;
out<<s;
}