#include<bits/stdc++.h>
using namespace std;
int main(){
	int n;
	int flag=1;
	cin>>n;
	while(n!=0){
		if(n%10>=n%100/10&&n>=10){
			cout<<"No";
			flag=0;
			break;
		}
		else{
			n/=10;
		}
	}
	if(flag) cout<<"Yes";
}

#include<bits/stdc++.h>
using namespace std;
#define int long long
signed main()
{
	string s;cin>>s;
	for(int i=0;i<s.size()-1;i++)
	{
		if(s[i]<=s[i+1])
		{
			cout<<"No";
			return 0;
		}
	}
	cout<<"Yes";
	return 0;
}