1 #include <iostream>
2 #include <stack>
3 #include <stdio.h>
4 using namespace std;
5 const int MAXN = 1000 + 10;
6
7 int n, target[MAXN];
8
9 int main(){
10 while(cin >> n){
11 stack<int> s;
12 int A = 1, B = 1;
13 for(int i = 1; i <= n; i++){
14 cin >> target[i];
15 }
16 int ok = 1;
17 while(B <= n){
18 if(A == target[B]){
19 A++;
20 B++;
21 }
22 else if(!s.empty() && s.top() == target[B]){
23 s.pop();
24 B++;
25 }
26 else if(A < n){
27 s.push(A++);
28 }
29 else{
30 ok = 0;
31 break;
32 }
33 }
34 printf("%s\n",ok ? "Yes" : "No");
35 }
36 return 0;
37 }
