C++ :

#include<bits/stdc++.h>
using namespace std;
int main(){
	int n,a[150000]={0},f[15]={0},i,j,f2[15]={0};
	char a1='A';
	cin>>n;
	for(i=0;i<n;i++)cin>>a[i];
	for(i=0;i<n;i++){
		if(a[i]<20)f[5]++;
		else if(a[i]<30)f[4]++;
		else if(a[i]<40)f[3]++;
		else if(a[i]<50)f[2]++;
		else if(a[i]<60)f[1]++;
		else f[0]++;
	}
	for(i=0;i<6;i++){
		f2[i]=f[i];
	}
	sort(f,f+6);
	for(i=5;i>=0;i--){
		for(j=0;j<6;j++){
			if(f[i]==f2[j]){
				a1+=j;
				cout<<a1<<":"<<f[i]<<endl;
				a1='A';
				f2[j]=-10;
				break;
			}
		}
	}
	return 0;
}

Python :

class dian:
    def _init_(self):
        self.dj=0
        self.sl=0
a=[]
for i in range(6):
    a.append(dian())
    a[i].dj=chr(ord("A")+i)
    a[i].sl=0
n=int(input())
sr=input().split()
for i in range(n):
    g=int(sr[i])
    if(g<20):
        a[5].sl=a[5].sl+1
    elif(g<29):
        a[4].sl=a[4].sl+1
    elif(g<39):
        a[3].sl=a[3].sl+1
    elif(g<49):
        a[2].sl=a[2].sl+1
    elif(g<59):
        a[1].sl=a[1].sl+1
    else:
        a[0].sl=a[0].sl+1
for i in range(6-1):
    for j in range(6-i-1):
        if(a[j].sl<a[j+1].sl):
            t=a[j]
            a[j]=a[j+1]
            a[j+1]=t
        elif(a[j].sl==a[j+1].sl and a[j].dj>a[j+1].dj):
            t=a[j]
            a[j]=a[j+1]
            a[j+1]=t
for i in range(6):
    print("{}:{}".format(a[i].dj,a[i].sl))