import java.util.*;
public class arrx{
public static void main(String[]argv){
Scanner sc=new Scanner(System.in);
while(sc.hasNext()){
int time =sc.nextInt();
int []a=new int[time];
int sum=0;
for(int i=0;i<time;i++){
a[i]=sc.nextInt();
sum+=a[i];
}
if(sum/time>=59)
System.out.println("no");
else
System.out.println("yes");
}
}
}
import java.util.*;
public class arrx{
public static void main(String[]argv){
Scanner sc=new Scanner(System.in);
while(sc.hasNext()){
int time =sc.nextInt();
int []a=new int[time];
int sum=0;
for(int i=0;i<time;i++){
a[i]=sc.nextInt();
sum+=a[i];
}
if(sum/time>=59)
System.out.println("no");
else
System.out.println("yes");
}
}
}
解出來的... 忘了小數也算