/*
* Author: Arpit Bhayani
* https://arpitbhayani.me
*/
#include <cmath>
#include <cstdio>
#include <cstdlib>
#include <climits>
#include <deque>
#include <iostream>
#include <list>
#include <limits>
#include <map>
#include <queue>
#include <set>
#include <stack>
#include <vector>
#define ll long long
#define MIN(a, b) a < b ? a : b
#define MAX(a, b) a > b ? a : b
using namespace std;
int readline(char *str) {
int i = 0;
char ch;
while((ch = getchar()) != '\n') {
str[i++] = ch;
}
str[i] = '\0';
return i;
}
int arr[10010];
int h[20020];
int main(int argc, char *argv[]) {
int n, d;
scanf("%d%d", &n, &d);
for(int i = 0 ; i < n ; i++) {
scanf("%d", &arr[i]);
h[arr[i]] = 1;
}
int count = 0;
for(int j = 1; j < n - 1; j++) {
int v = arr[j];
if(v - d >= 0 && v + d < 20020 && h[v-d] == 1 && h[v + d] == 1) {
count++;
}
}
printf("%d\n", count);
return 0;
}
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