void numar(int n,  int a[], int& k)

{

  int min=a[0], max=a[0], i;

  for (i=1; i<n; ++i){

       if (a[i]<min) min=a[i];

       if (a[i]>max) max=a[i];

  }

  int copiemin=min, z=1;

  while (copiemin>0) {

      z*=10; copiemin /=10;

  }

  k=max*z+min;

  return;

}