#if !__INCLUDE_LEVEL__

#include __FILE__

struct Solver {
void solve() {
	int n;cin>>n;
	V<int> a(n);
	V<V<int>> b(2005);
	rep(i,n){
		cin>>a[i];
		b[a[i]].emplace_back(i);
	}

	int ans=0;
	rep(i,n){
		rep(j,i+1,n){
			if(a[j]-10<1)continue;
			int l=LB(b[a[j]-10],i);
			int r=sz(b[a[i]+1])-UB(b[a[i]+1],j);
			ans+=l*r;
		}
	}
	cout<<ans<<endl;
}};

signed main() {
	int ts = 1;
	// scanf("%lld",&ts);
	rep(ti,ts) {
		Solver solver;
		solver.solve();
	}
	return 0;
}

#else

#include <bits/stdc++.h>
#include <atcoder/all>
using namespace atcoder;
// #include <ext/pb_ds/assoc_container.hpp>
// #include <ext/pb_ds/tree_policy.hpp>
// using namespace __gnu_pbds;

using namespace std;

#define int ll

using ll=long long;
using ld = long double;
using uint = unsigned;
using ull = unsigned long long;
using P=pair<int,int>;
using TP=tuple<int,int,int>;

const int INF = 1001001001;
const long long INFL = 3e18;
const int MAX = 2e6+5;

#define FOR1(a) for (ll _ = 0; _ < ll(a); ++_)
#define FOR2(i, a) for (ll i = 0; i < ll(a); ++i)
#define FOR3(i, a, b) for (ll i = a; i < ll(b); ++i)
#define FOR4(i, a, b, c) for (ll i = a; i < ll(b); i += (c))
#define FOR1_R(a) for (ll i = (a)-1; i >= ll(0); --i)
#define FOR2_R(i, a) for (ll i = (a)-1; i >= ll(0); --i)
#define FOR3_R(i, a, b) for (ll i = (b)-1; i >= ll(a); --i)
#define FOR4_R(i, a, b, c) for (ll i = (b)-1; i >= ll(a); i -= (c))
#define overload4(a, b, c, d, e, ...) e
#define rep(...) overload4(__VA_ARGS__, FOR4, FOR3, FOR2, FOR1)(__VA_ARGS__)
#define rrep(...) overload4(__VA_ARGS__, FOR4_R, FOR3_R, FOR2_R, FOR1_R)(__VA_ARGS__)
#define fore(i,a) for(auto &i:a)

#define all(x) x.begin(),x.end() 
#define allr(x) x.rbegin(),x.rend() 
#define sz(x) ((int)(x).size())
#define bp(x) (__builtin_popcountll((long long)(x)))
#define elif else if
#define mpa make_pair
#define bit(n) (1LL<<(n))
#define LB(c, x) distance((c).begin(), lower_bound(all(c), (x)))
#define UB(c, x) distance((c).begin(), upper_bound(all(c), (x)))

template<typename T> using V = vector<T>;
template<typename T> using max_heap = priority_queue<T>;
template<typename T> using min_heap = priority_queue<T, vector<T>, greater<>>;
template<typename T>bool chmax(T &a, const T &b) { if (a<b) { a=b; return 1; } return 0; }
template<typename T>bool chmin(T &a, const T &b) { if (b<a) { a=b; return 1; } return 0; }
template<typename T>string join(const T&v,const string& d=""){stringstream s;rep(i,sz(v))(i?s<<d:s)<<v[i];return s.str();}
template<typename T>ostream& operator<<(ostream&o,const vector<T>&v){if(sz(v))o<<join(v," ");return o;}
template<typename T1,typename T2>ostream& operator<<(ostream&o,const pair<T1,T2>&v){return o<<v.first<<","<<v.second;}
template<typename Tx, typename Ty>Tx dup(Tx x, Ty y){return (x+y-1)/y;}
template<typename T>ll suma(const vector<T>&a){ll res(0);for(auto&&x:a)res+=x;return res;}
template<typename T>ll suma(const V<V<T>>&a){ll res(0);for(auto&&x:a)res+=suma(x);return res;}
template<typename T>void uni(T& a){sort(all(a));a.erase(unique(all(a)),a.end());}
template<typename T>void prepend(vector<T>&a,const T&x){a.insert(a.begin(),x);}
template<typename T>T vgcd(T m, T n) {return std::gcd(m, n);}
template<typename T, typename... Args>T vgcd(T a, Args... args) {return vgcd(a, vgcd(args...));}

void print(){ putchar(' '); }
void print(bool a){ printf("%d", a); }
// void print(int a){ printf("%d", a); }
void print(unsigned a){ printf("%u", a); }
void print(long a){ printf("%ld", a); }
void print(long long a){ printf("%lld", a); }
void print(unsigned long long a){ printf("%llu", a); }
void print(char a){ printf("%c", a); }
void print(char *a){ printf("%s", a); }
void print(const char *a){ printf("%s", a); }
void print(double a){ printf("%.15f", a); }
void print(long double a){ printf("%.15Lf", a); }
void print(const string& a){ for(auto&& i : a) print(i); }
template<typename T> void print(const complex<T>& a){ if(a.real() >= 0) print('+'); print(a.real()); if(a.imag() >= 0) print('+'); print(a.imag()); print('i'); }
template<typename T> void print(const vector<T>&);
template<typename T, size_t size> void print(const array<T, size>&);
template<typename T, typename L> void print(const pair<T, L>& p);
template<typename T, size_t size> void print(const T (&)[size]);
template<typename T> void print(const vector<T>& a){ if(a.empty()) return; print(a[0]); for(auto i = a.begin(); ++i != a.end(); ){ putchar(' '); print(*i); } }
template<typename T> void print(const deque<T>& a){ if(a.empty()) return; print(a[0]); for(auto i = a.begin(); ++i != a.end(); ){ putchar(' '); print(*i); } }
template<typename T, size_t size> void print(const array<T, size>& a){ print(a[0]); for(auto i = a.begin(); ++i != a.end(); ){ putchar(' '); print(*i); } }
template<typename T, typename L> void print(const pair<T, L>& p){ print(p.first); putchar(' '); print(p.second); }
template<typename T, size_t size> void print(const T (&a)[size]){ print(a[0]); for(auto i = a; ++i != end(a); ){ putchar(' '); print(*i); } }
template<typename T> void print(const T& a){ cout << a; }
int out(){ putchar('\n'); return 0; }
template<typename T> int out(const T& t){ print(t); putchar('\n'); return 0; }
template<typename Head, typename... Tail> int out(const Head& head, const Tail&... tail){ print(head); putchar(' '); out(tail...); return 0; }


ll binary_search(function<bool(ll)> check, ll ok, ll ng) {
assert(check(ok));
	while (abs(ok - ng) > 1) {
		auto x = (ng + ok) / 2;
		if (check(x))
			ok = x;
		else
			ng = x;
	}
	return ok;
}

#endif