#include <fstream>

using namespace std;

int n,i,d,k,a[1000001],st,dp[1000001];
ifstream fi("zombie.in");
ofstream fo("zombie.out");

int main()
{
    fi>>d>>n>>k;
    for(i=1;i<=n;i++)
    {
        fi>>a[i];
    }
    st=1;
    dp[1]=1;
    for(i=2;i<=n;i++)
        {
         while(a[i]-a[st]>d)
                st++;
         dp[i]=min(dp[i-1]+1,dp[st-1]+k);
        }
    fo<<dp[n];
}