#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const double pi=3.141592653589793;
typedef unsigned long long ull;
typedef long double ldouble;
const ll INF=1e18;
#define rep(i, n) for(ll i = 0; i < (ll)(n); i++)
#define rep2(i, s, n) for (ll i = (s); i < (ll)(n); i++)
template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1; } return 0; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1; } return 0; }

vector<vector<int> > c(2*10e5+1);

void solve(int x, int y) {

}

int main(){
  int n;
  cin >> n;
  vector<int> a(n+1);
  
  rep(i, n){
    cin >> a[i+1];
  }
  
  while(true){
    bool ok = false;
    bool end = true;
    rep2(i, 1, n+1){
      if(a[i] == i) {
        rep2(j, 1, i) {
          a[j]++;
        }
        a[i] = 0;
        ok = true;
        break;
      }
      else if(end && a[i] != 0) {
        end = false;
      }
    }
    if(!ok && end) {
      cout << "Yes" << endl;
      return 0;
    }
    else if(!ok && !end) {
      cout << "No" << endl;
      return 0;
    }
  }
}