Untitled

#include<bits/stdc++.h>
#define MAX_CHAR 26
using namespace std;
string S;
int k;
int PoWMod(int n){
    int tong = 1;
    for(int i = 1; i <= 2; i++){
        tong *= n;
    }
    return tong;
}
void Min_String(){
    cin>>k;
    cin.ignore();
    getline(cin,S);
    int F[MAX_CHAR];
    memset(F, 0, sizeof(F));
    for(int i=0;i < (int)S.size();i++){
        F[S[i]-'a']++;
    }
    priority_queue<int> Q;
    for(int i=0;i<MAX_CHAR;i++){
        Q.push(F[i]);
    }
    while(k--){
        int t=Q.top();
        Q.pop();
        t--;
        Q.push(t);
    }
    long long tong = 0;
    while(!Q.empty()){
        int s=Q.top();
        tong += (1ll)*PoWMod(s);
        Q.pop();
    }
    cout << tong;
}
int main(){
    Min_String();
}