int main()
{
char str[1001],a[1001],b[1001],ch,al[1001],bl[1001];
int i,n,k=0,j=0,p,q,t;
scanf("%d", &n);
scanf("%s", str);
for (i = 0; i < n; i++)
{
ch = str[i];
if (ch >= 'A' && ch <= 'Z')
{
al[k] = i;
a[k] = str[i];
k++;
}
else if (ch >= '0' && ch <= '9')
{
bl[j] = i;
b[j] = str[i];
j++;
}
}
for (p = 0; p < k; p++)
{
for (q = p + 1; q < k; q++)
{
if (a[q] < a[p])
{
t = a[q];
a[q] = a[p];
a[p] = t;
}
}
}
for (p = 0; p < j; p++)
{
for (q = p + 1; q < j; q++)
{
if (b[q] > b[p])
{
t = b[q];
b[q] = b[p];
b[p] = t;
}
}
}
for (i=0;i<k;i++)
{
str[al[i]] = a[i];
}
for(i=0;i<j;i++)
{
str[bl[i]]=b[i];
}
printf("%s",str);
return 0;
}