# include <fstream>
# include <iostream>
# define nmax 1000005
using namespace std;
ifstream fi("zombie.in");
ofstream fo("zombie.out");
int S[nmax];
int main(void)
{
    int n,d,k;
    long long M=0;
    fi>>d>>n>>k;
    for (int i=1;i<=n;++i) fi>>S[i];
    for (int i=1;i<=n;++i)
    {
        int p=S[i],f=i;
        while (S[i+1]<=p+d && i<n) ++i;
        if (k<i-f+1) M+=k;else M+=(i-f+1);
    }
    fo<<M<<"\n";
}