#include <iostream>
#include <fstream>
using namespace std;

ifstream in("zombie.in");
ofstream out("zombie.out");

int N,d,k,dr,st;

int v[1000005];
int cost[1000005];

int main()
{
    in>>d>>N>>k;
    for(int i=1;i<=N;i++)
    {
        in>>v[i];
    }

    dr=st=1;

    while(dr<=N)
    {
        while(v[dr]-v[st]>d)
        {
            st++;
        }
        if(cost[st-1]+k<cost[dr-1]+1)
        {
            cost[dr]=cost[st-1]+k;
        }
        else{
            cost [dr]=cost [dr-1]+1;
        }
        dr++;
    }
    out<<cost [N];
    return 0;
}