You are given an alphabet consisting of n letters, your task is to make a string of the maximum possible length so that the following conditions are satisfied:

• the i-th letter occurs in the string no more than a_i times;
• the number of occurrences of each letter in the string must be distinct for all the letters that occurred in the string at least once.

The first line of the input contains a single integer n (2  ≤  n  ≤  26) — the number of letters in the alphabet.

The next line contains n integers a_i (1 ≤ a_i ≤ 10⁹) — i-th of these integers gives the limitation on the number of occurrences of the i-th character in the string.

Print a single integer — the maximum length of the string that meets all the requirements.

For convenience let's consider an alphabet consisting of three letters: "a", "b", "c". In the first sample, some of the optimal strings are: "cccaabbccbb", "aabcbcbcbcb". In the second sample some of the optimal strings are: "acc", "cbc".

题意：n种字母 每种字母分别最多出现ai次 要求 每种字母出现次数都不同

题解 a[]排序 当前字母最多出现次数未被占据 则 exm-- 累加

#include<bits/stdc++.h>

using namespace std;

#define LL  __int64

int n;

int a[30];

map<int,int> mp;

int main()

{

    scanf("%d",&n);

    mp.clear();

    for(int i=0;i<n;i++)

        scanf("%d",&a[i]);

    sort(a,a+n);

    LL ans=a[n-1];

    mp[a[n-1]]=1;

    for(int i=n-2;i>=0;i--)

    {

         int exm=a[i];

         while(mp[exm]&&exm>0)

         {

             exm--;

         }

         ans+=exm;

         mp[exm]=1;

    }

    printf("%I64d\n",ans);

    return 0;

}