include <bits/stdc++.h>

using namespace std;

int main() {

int num, num2 = 0, a[10] = {0}, n, num1 = 0;
cin >> num;
while (num != 0) {
	int x = num % 10;
	a[x]++;
	num = num / 10;
}
int flag = 0;
for (int i = 0; i <= 9; i++) {
	while (a[i]--) {

		if (flag == 0) {
			num1 = num1 * 10 + i;
			flag = 1;
		} else {
			num2 = num2 * 10 + i;
			flag = 0;
		}
	}
}
n = num1 + num2;
cout << n;
return 0;

}