#include <bits/stdc++.h>
using namespace std;
int main(){
    int n,i,j;
    cin>>n;
    int a[n],s[6]={0};
    char d[6]={'A','B','C','D','E','F'};
    for(i=0;i<n;i++){
        cin>>a[i];
        if(a[i]>59){
            s[0]++; 
        }else if(a[i]>49){
            s[1]++;
        }else if(a[i]>39){
            s[2]++;
        }else if(a[i]>29){
            s[3]++; 
        }else if(a[i]>19){
            s[4]++; 
        }else{
            s[5]++;
        }
    }
    for(j=5;j>0;j--){
        for(i=0;i<j;i++){
            if(s[i]<s[i+1]){
                swap(s[i],s[i+1]);
                swap(d[i],d[i+1]);
            }
        }
    }
    for(i=0;i<6;i++){
        cout<<d[i]<<":"<<s[i]<<endl;
    }
}
/**************************************************************
	Problem: 1314
	User: wangyiyang
	Language: C++
	Result: Accepted
	Time:9 ms
	Memory:2072 kb
****************************************************************/