import std.stdio,
       std.conv,
       std.string,
       std.range,
       std.algorithm;

void main()
{
    auto N = readln.strip.to!int;
    int[] A, B, C;
    foreach (_; 0 .. N)
    {
        auto input = readln.split.to!(int[]);
        A ~= input[0];
        B ~= input[1];
        C ~= input[2];
    }

    auto inventory = new int[11];
    int ans;
    chain(A, B, C).each!(item => inventory[item]++);
    ans =  inventory.map!"a/2".sum;
    ans += inventory.map!"a%2".count!"a>0" / 4;
    ans.writeln;
}