#include<bits/stdc++.h>
#include"testlib.h"
using namespace std;
using ll = long long;

const ll Nmin = 1, Nmax = 100'000;
const ll Amin = 0, Amax = 100'000;

int main(){
    registerValidation();
    ll n = inf.readLong(Nmin,Nmax);
    inf.readEoln();
    vector<ll> a(n);
    for (ll i = 0; i < n; i++){
        if (i != 0){
            inf.readSpace();
        }
        a[i] = inf.readLong(Amin,Amax);
    }
    inf.readEoln();
    inf.readEof();
    ensuref(Amax >= a[0],"Amax >= A_1");
    for (ll i = 1; i < n; i++){
        ensuref(a[i-1] >= a[i], "A_i >= A_{i+1}");
    }
    ensuref(a[n-1] >= Amin, "A_N >= Amin");
}