#include<fstream>
using namespace std;ifstream fin("zombie.in");ofstream fout("zombie.out");int sol,n,d,k,i,c,v[2000001];int main() {fin>>d>>n>>k;for(i=1;i<=n;i++){fin>>v[i];}for(i=1;i<=n;i++){if(v[i+k]-v[i]>d){i++;sol++;}else {c=i;while(v[i+k]-v[c]<=d&&i<=n){++i;}sol+=k;}}fout<<sol;return 0;}