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

int main(){
	int N, A, prev, count = 0, ans = 0;
    cin >> N;
    for(int i = 0; i < N; i++){
        cin >> A;
        if(i == 0 || prev + 1 == A){
            ++count;
        }else{
            ans += (count - 1) * count / 2;
            count = 1;
        }
        prev = A;
    }
    ans += (count - 1) * count / 2;
    cout << ans << endl;
}