import java.util.Scanner; class no216{ public static void main(String[] args) { Scanner stdIn=new Scanner(System.in); int n,a[]=new int[100],b,c[]=new int[101],i,m=0; n=stdIn.nextInt(); for(i=0;im) m=c[i]; if(m<=c[0]) System.out.print("YES"); else System.out.print("NO"); } }