#include <iostream>
#include <fstream>

using namespace std;

const int Nmax = 1000000;

long long N, K, D;
int v[Nmax + 1];

int main()
{
    ifstream f("zombie.in");
    ofstream g("zombie.out");

    f >> D >> N >> K;

    for ( int i = 1; i <= N; ++i )
            f >> v[i];

    long long sol = 0;

    for ( int i = 1; i <= N; )
    {
        int j = i;

        while ( j + 1 <= N && v[j + 1] - v[i] <= D ) j++;

        sol += min( K, 1LL * ( j - i + 1 ) );

        i = j + 1;
    }

    g << sol << "\n";

    return 0;
}