#include <iostream>
#include <cmath>
#include <algorithm>
#include <string>
#include <vector>
#include <map>
#include <unordered_map>
#include <queue>
#include <set>
#include <unordered_set>
#include <complex>
#include <list>
#include <cassert>
#include <chrono>
#include <random>
#include <stack>
#include <iomanip>
#include <fstream>
using namespace std;
#define endl "\n"
#define ll long long
const int INF = 1e9+7;
const int MOD = 1e9+7;
vector<int> construct_range(int m, int k){
return {};
}
bool check(int d1, int d2, int d3, int h1, int h2, int h3){
return (((d1 == h1 && d2 == h2 && d3 == h3) ||
(d1 == h1 && d2 == h3 && d3 == h2) ||
(d1 == h2 && d2 == h1 && d3 == h3) ||
(d1 == h2 && d2 == h3 && d3 == h1) ||
(d1 == h3 && d2 == h1 && d3 == h2) ||
(d1 == h3 && d2 == h2 && d3 == h1)));
}
ll sb1(int n, vector<int> &a){
ll cnt = 0;
for(int i = 0; i < n; i++){
for(int j = i; j < n; j++){
for(int k = j; k < n; k++){
cnt += check(j-i, k-j, k-i, a[i], a[j], a[k]);
}
}
}
return cnt;
}
ll sb2(int n, vector<int> &a){
ll cnt = 0;
for(int i = 0; i < n; i++){
for(int j = i+1; j <= min(i+10, n-1); j++){
for(int k = j; k <= min(j+10, n-1); k++){
cnt += check(j-i, k-j, k-i, a[i], a[j], a[k]);
}
}
}
return cnt;
}
ll count_triples(vector<int> a){
int n = (int)a.size();
if(n <= 100){
return sb1(n, a);
} else if(*max_element(a.begin(), a.end()) <= 10) {
return sb2(n, a);
}
return sb1(n, a);
}
