#include<bits/stdc++.h>
using namespace std;
signed main(){
	int a[4];
	char c;
	cin>>a[1]>>c>>a[2]>>c>>a[3];
	sort(a+1,a+4);
	cout<<a[3]<<c<<a[2]<<c<<a[1];
}

sort一下awa。

#include<bits/stdc++.h>
#define int long long
#define INF 0x3f3f3f
using namespace std;
int a[5];
signed main(){
	scanf("%d,%d,%d",&a[1],&a[2],&a[3]);
	sort(a+1,a+4);
	cout<<a[3]<<","<<a[2]<<","<<a[1];
	return 0;
}