#include <cstdio>
using namespace std;

#define NMAX 1000005
int v[ NMAX ];

int main()
{

    freopen("zombie.in","r",stdin);
    freopen("zombie.out","w",stdout);

    int n, i, j, k, d;
    long long ch = 0;


    scanf("%d%d%d",&d,&n,&k);
    for( i = 1; i <= n; ++i ) scanf("%d",&v[ i ]);

    for( j = i = 1; i <= n; ++i ){
        while( j < n && v[ j + 1 ] - v[ i ] <= d ) ++j;
        if( j - i >= k ){
            ch += k;
            i = j;
        }
        else ++ch;
    }

    printf("%lld",ch);

    return 0;
}