def beautifulTriplets(d, arr):
    ans = 0
    for a in range(len(arr)):
        for b in range(a + 1, len(arr)):
            if arr[b] - arr[a] == d:
                for c in range(b + 1, len(arr)):
                    if arr[c] - arr[b] == d:
                        ans += 1
    return ans

int beautifulTriplets(int d, vector<int> arr) {
    map<int, int> mp;
    int result = 0;
    for (int a : arr) {
        mp[a] += 1;
        result += mp[a-d]*mp[a-2*d];
    }
    return result;
}

def beautifulTriplets(d, arr):
    c=0
    n=len(arr)
    for i in range(n):
        for j in range(i+1,n):
            if arr[j]-arr[i]==d:
                for k in range(j+1,n):
                    if arr[k]-arr[j]==d:
                        c+=1
    return c

int beautifulTriplets(int d, vector<int> arr) {
  int res = 0;
  for(auto it = arr.begin(); it < arr.end(); it++) {
    auto a = find(it+1, arr.end(), *(it)+d);
    if(a != arr.end()) {
      auto b = find(a+1, arr.end(), *(a)+d);
        if(b != arr.end()) res++;
    }
  }
  return res;
}