#include<iostream>
using namespace std;
int main(){
    int n,a[100],i,d=0;
    cin>>n;
    for(i=0;i<n;i++){
        cin>>a[i];
    }
    for(i=0;i<n-1;i++){
        if(a[i]>=90){
            d++;
        }
    }
    for(i=0;i<n-1;i++){
        if(a[i]<60||n<2){
            cout<<"no";
            return 0;
        }
    }
    if(d>=5){
        cout<<"1";
    }else if(d==3||d==4){
        cout<<"2";
    }else if(d==2){
        cout<<"3";
    }
     
}
/**************************************************************
	Problem: 1429
	User: wangyiyang
	Language: C++
	Result: Accepted
	Time:12 ms
	Memory:2072 kb
****************************************************************/