#include <stdio.h>

int main() {
    int n,cnt=0;
    scanf("%d",&n);
    char s[n],S[n];
    scanf("%s",s);
    for ( int i=0; i<n; i++ )
    {
        if ( s[i]>='a' && s[i]<='z' )
        {
            S[cnt] = s[i];
            cnt++;
        } 
    }
    for ( int i=0; i<n; i++ )
    {
        if ( s[i]>='0' && s[i]<='9' )
            {
                S[cnt] = s[i];
                cnt++;
            }
    }
    for ( int i=0; i<n; i++ )
    {
        if ( s[i]>='A' && s[i]<='Z' )
        {
            S[cnt] = s[i];
            cnt++;
        }
    }
    S[cnt] = '\0';//避免输出乱码
    printf("%s",S);

    return 0;
}