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



int main(){
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    ll N;
    cin>>N;
    bool OK=1;
    for(int i=0;i<N;i++){
        ll a;
        cin>>a;
        if(a>0){
            cout<<"Yes\n";
            return 0;
        }
    }
    cout<<"No\n";
    return 0;
}