#include <stdio.h>
int main() {
int n, a[10], count = 0;
scanf("%d", &n);
for (int i = 0; n > 0; i++) {
a[i] = n % 10;
n /= 10;
count++;
}
for (int i = 0; i < count; i++) {
if (a[i] < a[j]) {
int temp = a[i];
a[i] = a[j];
a[j] = temp;
}
}
}
for (int i = 0; i < count; i++) {
printf("%d", a[i]);
}
return 0;
}