var obj = init(); Main(); function nextInt(){return myconv(next(),1);} function nextStrArray(){return myconv(next(),2);}//半角スペース分割 function nextIntArray(){return myconv(next(),4);}//半角スペース + 数値化 function nextCharArray(){return myconv(next(),6);}//1文字分割 function next(){return obj.next();} function hasNext(){return obj.hasNext();} function myin(){return require("fs").readFileSync("/dev/stdin", "utf8").trim().split("\n");} function init(){ var inputFile = myin(); var returnObj = { "list" : inputFile, "index" : 0, "max" : inputFile.length, "hasNext" : function(){return (this.index < this.max);}, "next" : function(){if(!this.hasNext()){return "";}else{var returnInput = this.list[this.index];this.index++;return returnInput;}} }; return returnObj; } function myout(t){console.log(t);}//標準出力 function myerr(t){console.error(t);}//標準エラー出力 //[no]要素の扱い。数値型 //不明値、異常時:引数そのまま返す 1:数値へ変換 //2:半角SPで分割 4:半角SPで分割し、数値配列へ //6:1文字で分割 7:1文字で分割し、数値配列へ //8:半角SPで結合 9:改行で結合 0:文字なしで結合 function myconv(i,no){try{switch(no){case 1:return parseInt(i);case 2:return i.split(" ");case 4:return i.split(" ").map((a)=>Number(a));case 6:return i.split("");case 7:return i.split("").map((a)=>Number(a));case 8:return i.join(" ");case 9:return i.join("\n");case 0:return i.join("");default:return i;}}catch(e){return i;}} function Main(){ var N = nextInt(); var list = new Array(10).fill(0); for(var i = 0; i < N; i++){ var tmp = nextIntArray(); list[tmp[0] - 1]++; list[tmp[1] - 1]++; list[tmp[2] - 1]++; } var one = 0; var output = 0; for(var i = 0; i < 10; i++){ output += Math.floor(list[i] / 2); one += list[i] % 2; } output += Math.floor(one / 4); myout(output); }