#include<stdio.h>

void main(){
    int a[11];
    int n,i,c=0,b=0;
    scanf("%d",&n);
    
    for(i=0;i<n;i++){
        scanf("%d",&a[i]);
    }
    
    for(i=0;i<n;i++){
        if(a[i]>=90){
            c++;
        }
        if(a[i]<60){
            b++;
        }
    }
    
    if(b==0){
        if(c>=5){
            printf("%d",1);
        }else if(c==3||c==4){
            printf("%d",2);
        }else if(c==2){
            printf("%d",3);
        }
    }else{
        printf("%s","no");
    }
}
/**************************************************************
	Problem: 1429
	User: admin
	Language: C
	Result: Accepted
	Time:20 ms
	Memory:1144 kb
****************************************************************/