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

long long n, p, m, j;
long long u[200001];

int main(){
    cin >> n;
        
    for(int i = 0; i < n; i++){
        cin >> p;
        u[p] = i + 1;
    }
    
    j = n;
    m = n * (n + 1) / 2;
    
    while(j > 1 && u[j] > u[j - 1] * 2){
        m -= u[j];
        j--;
    }
    
    if(j > 1)
        m -= u[j] * 2;
    else
        m = 0;
        
    cout << m << endl;
}