#include <iostream>
#include <algorithm>
using namespace std;
int main() {
int tab[4];
for(int i=0;i<4;i++)cin>>tab[i]; // cin>>tab[0]>>tab[1]>>tab[2]>>tab[3];
sort(tab,tab+4);
for(int i=0;i<4;i++)cout<<tab[i];//cout<<tab[0]<<tab[1]<<tab[2]<<tab[3];
return 0;
}
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