/*
https://yukicoder.me/problems/no/2836
*/

#include<iostream>
#include<string>
#include<queue>
#include<vector>
#include<cassert>
#include<random>
#include<set>
#include<map>
#include<cassert>
#include<unordered_map>
#include<bitset>
#include<numeric>
#include<algorithm>
using namespace std;
typedef long long ll;
const int inf=1<<30;
const ll INF=1LL<<62;
typedef pair<int,ll> P;
typedef pair<int,P> PP; 
const ll MOD=998244353;

int main(){
    
    int N;
    cin>>N;
    vector<int> A(N);
    for(int i=0;i<N;i++){
        cin>>A[i];
    }
    int v=*min_element(A.begin(),A.end());
        
    if(v<=1){
        cout<<"Yes"<<endl;
        return 0;
    }
    
    cout<<"No"<<endl;
}