#include <bits/stdc++.h>
using namespace std;
int main()
{
int N;cin >> N;
string S;cin >> S;
char temp = 0;
for (int i = 0; i < N -1; i++)
{
for (int j = 0; j < N -1; j++)
{
if (S[j] > S[j +1])
{
temp = S[j];
S[j] = S[j +1];
S[j +1] = temp;
}
}
}
cout << S;
}
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