#include <stdio.h>
#define INF 1500000000
#define MAXN 1000000
int v[MAXN+1];
long long d[MAXN+1];
int main(){
    int t, n, k, i, p;
    FILE *fin, *fout;
    fin=fopen("zombie.in", "r");
    fout=fopen("zombie.out", "w");
    fscanf(fin, "%d%d%d", &t, &n, &k);
    d[0]=0;
    v[0]=-INF;
    p=0;
    for(i=1; i<=n; i++){
        fscanf(fin, "%d", &v[i]);
        while(v[i]>v[p+1]+t){
            p++;
        }
        d[i]=d[i-1]+1;
        if(d[i]>k+d[p]){
            d[i]=k+d[p];
        }
    }
    fprintf(fout, "%d\n", d[n]);
    fclose(fin);
    fclose(fout);
    return 0;
}