import strutils, sequtils, sets

proc main =
    let N = parseInt readLine stdin
    var dic = initSet[int]()
    var cnt = 0
    
    for i in 0 ..< N:
        var abc = map(split readLine stdin, parseInt)
        for v in abc:
            if v in dic:
                cnt += 1
                excl dic, v
            else:
                incl dic, v
    
    cnt += len(dic) div 4
    echo cnt

main()