#include
#include
void sort(char* s, int n)
{
int i = 0, j = 0, index = 0;
char c;
for (; i < n; i++)
{
c = s[i];
index = i;
for (j = i + 1; j < n; j++)
{
if (s[j] < c)
{
index = j;
c = s[j];
}
}
if (index != i)
{
c = s[index];
s[index] = s[i];
s[i] = c;
}
}
}
int main()
{
char s[20];
gets(s);
sort(s, strlen(s));
puts(s);
return 0;
}