#include <iostream>
#include <string>
#include <vector>
#include <math.h>
using namespace std;
string str ;
int main()
{
    int i = 0 , n , half=0 , quart=0 , h_q=0;
    float sum = 0 ;
    scanf ("%d",&n);
    for ( i = 0 ; i < n ; i ++ )
    {
        cin >> str ;
        if(str[2] == '2' ) half++;
        if ( str[2] == '4' && str[0] != '3' ) quart++ ;
        if ( str[0] == '3' ) h_q++ ;
    }
    for ( ; quart > 0 || h_q > 0 ; h_q-- , quart-- )
    {
        sum += 1 ;
    }
    if ( quart % 2 == 0 )
    {
        half += quart / 2 ;
        quart = 0 ;
    }
    else if ( quart % 2 != 0 )
    {
        sum += ceil( quart / 2 ) - 1 ;
        quart = 1 ;
    }
     if ( half % 2 == 0 )
    {
        sum += half / 2 ;
        half = 0 ;
    }
    else if ( half % 2 != 0 )
    {
        sum += ceil( half / 2 ) - 1 ;
        half = 1 ;
    }
    if ( half == 1 ) sum += half ;
    if ( quart == 1 ) sum += 1 ;
    for ( ; h_q >=0 ; h_q--  )  sum += 1 ;
    i = sum ;
    printf ("%d",i) ;
    return 0;
}