#include<fstream>
using namespace std;
ifstream fin("numere6.in");
ofstream fout("numere6.out");
int main ()
{
int a,b,x[20],i=0;
fin>>a>>b;
while(a)
{
i++;
x[i]=a%10;
a/=10;
}
while(b)
{
i++;
x[i]=b%10;
b/=10;
}
for(int z=1;z<=i;z++)
for(int v=z+1;v<=i;v++)
if(x[v]>x[z])
{
int aux=x[v];
x[v]=x[z];
x[z]=aux;
}
for(int z=1;z<=i;z++)
fout<<x[z];
fin.close();
fout.close();
return 0;
}