#include <bits/stdc++.h>
using namespace std;

using ll = long long;
using ull = unsigned long long;
using ld = long double;
template<class t> using vc = vector<t>;
template<class t> using vvc = vc<vc<t>>;
using pi = pair<int,int>;
using vi = vc<int>;
using vvi = vvc<int>;

#define rep(i,a,b) for (int i = a; i < b; i++)
#define irep(i,a,b) for (int i = a; i > b; i--)
#define print(n) cout << n << endl
#define pritn(n) print(n)
#define rup(a,b) (a+b-1)/b
#define input(A,N) rep(i,0,N) cin>>A[i];


int main(){
    cout << fixed << setprecision(15);
    
    int N ;
    cin >> N;
    vc<ll> A(N);
    input(A,N);
    ll count = 0;
    ll now = 0;
    int d = 0;
    rep(i,1,N){
        if (1){
            if (d==0){
                if (A[i]-A[i-1]==1||A[i]-A[i-1]==-1){
                d = A[i] - A[i-1];
                now = 2;
                continue;}
            }else{
                if (d==A[i]-A[i-1]){
                    now += 1;
                    continue;
                }else{
                    d = 0;
                    count += now*(now-1)/2;
                    i --;
                    now = 0;
                }
            }
        }
    }
    count += now*(now-1)/2;print(count);
    
    //system("pause");
    return 0;
}