126?

#include<iostream>
using namespace std;
int main()
 {
  int ap[100],aux,n,r=0,i;
  cin>>n;
  n=aux;
   while(aux)
    {
     ap[aux%10]++;
     aux=aux/10;
    }
   for(i=9;i>=0;i--)
     {
      r=r*10+i;
      ap[i]--;
     }
    if(n==r)
     cout<<"nu exista";
       else
     cout<<"exista";
 }