火车进站

#include <iostream>
#include <stack>
#include <stdio.h>
using namespace std;
const int MAXN = 1000 + 10;

int n, target[MAXN];

int main(){
    while(cin >> n){
        stack<int>  s;
        int A = 1, B = 1;
        for(int i = 1; i <= n; i++){
            cin >> target[i];
        }
        int ok = 1; 
        while(B <= n){
            if(A == target[B]){
                A++;
                B++;
            }
            else if(!s.empty() && s.top() == target[B]){
                s.pop();
                B++;
            }
            else if(A < n){
                s.push(A++);
            }
            else{
                ok = 0; 
                break;
            }
        }
        printf("%s\n",ok ? "Yes" : "No");
    }
    return 0;
}