#include<bits/stdc++.h>
using namespace std;
using ll=long long;
using pii=pair<int,int>;

#define all(a) a.begin(),a.end()
#define pb push_back
#define sz(a) ((int)a.size())

const int N=2005,mod=998244353;
int add(int x, int y){x+=y; if(x>=mod) x-=mod; return x;}
int sub(int x, int y){x-=y; if(x<0) x+=mod; return x;}
int mul(int x, int y){return ((ll)x)*y%mod;}
int Pow(int x, ll y=mod-2){int res=1; for(; y; x=mul(x,x),y>>=1) if(y&1) res=mul(res,x); return res;}

int n,a[N],cnt[N];

signed main(){
    ios_base::sync_with_stdio(0),cin.tie(0);
    cout << fixed << setprecision(20);
    cin >> n;
    for(int i=0; i<n; ++i) cin >> a[i];
    ll res=0;
    for(int i=n-1; i>=0; --i){
        int cur=0;
        for(int j=i-1; j>=0; --j){
            if(a[i]==a[j]+10) res+=cur;
            if(a[j]>a[i]) cur+=cnt[a[j]+1];
        }
        cnt[a[i]]++;
    }
    cout << res << "\n";
}