#include <stdio.h>
#include <stdlib.h>
#include <string.h>

int min ( int a , int b ){
    if ( a < b )
        return a;
    return b;
}

int main ( int argc , char * argv[] ) {

    int t;

    while ( scanf("%d" , &t) != EOF ) {

        int s[3];

        memset(s,0,sizeof(s));

        while ( t-- ) {

            char str[4];

            scanf("%s" , str );

            if ( str[0] == '1' && str[2] == '4' ) {
                s[0]++;
            }
            else if ( str[0] == '1' && str[2] == '2' ) {
                s[1]++;
            }
            else if ( str[0] == '3' && str[2] == '4' ) {
                s[2]++;
            }

        }

        // Abotrika's 1 pizza
        int n = 1;
        int d = 0;

        d = min( s[0] , s[2] );
        n += d;
        s[0] -= d;
        s[2] -= d;


        //Combining two 1/2 into 1 pizza
        n += s[1]/2;
        s[1] = s[1] % 2;

        //Combining 2 1/4th and 1 1/2

        if ( s[1] == 1 && s[0] >= 2 ) {
            n += 1;
            s[0] -= 2;
            s[1] = 0;
        }

        if ( s[1] == 1 && s[0] == 1 ) {
            n += 1;
            s[0] = 0;
            s[1] = 0;
        }

        //Combining 2 1/4th and 1 1/2
        d = min ( s[0]/4 , s[1]);
        n += d;
        s[0] -= (2 * d);
        s[1] -= d;

        //Combingin all 1/4ths
        n += s[0]/4;
        if ( s[0] % 4 == 0 )
            s[0] = 0;
        else
            s[0] = 1;

        // Rest all will be comming form 1 pizza each

        n += (s[0] + s[1] + s[2]);

        printf("%d\n" , n);
    }

    return 0;
}