//↓見なくていいよ！ここから--------------------------------------------------
var read = require('readline').createInterface({
  input: process.stdin,
  output: process.stdout
});
var obj;
var inLine = [];
read.on('line', function(input){inLine.push(input);});
read.on('close', function(){
  obj = init(inLine);
  console.error("\n");
  var start = Date.now();
  Main();
  var end = Date.now() - start;
  myerr("time : " + (end) + "ms");
  myerr("memory : " + Math.round(process.memoryUsage().heapTotal / 1024) + "KB");
});
function makeClone(obj){return JSON.parse(JSON.stringify(obj));}
function nextInt(){return myconv(next(),1);} function nextStrArray(){return myconv(next(),2);}
function nextIntArray(){return myconv(next(),4);} function nextCharArray(){return myconv(next(),6);}
function next(){return obj.next();} function hasNext(){return obj.hasNext();}
function init(input){  
  var returnObj = {
    list : input, index : 0, max : input.length,
    hasNext : function(){return (this.index < this.max);},
    next : function(){if(!this.hasNext()){throw "ArrayIndexOutOfBoundsException これ以上ないよ";}else{var returnInput = this.list[this.index];this.index++;return returnInput;}}
  };
  return returnObj;
}
function myout(s){console.log(s);}
function myerr(s){console.error("debug:" + require("util").inspect(s,false,null));}
//[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(Number);case 6:return i.split("");case 7:return i.split("").map(Number);case 8:return i.join(" ");case 9:return i.join("\n");case 0:return i.join("");default:return i;}}catch(e){return i;}}

//↑見なくていいよ！ここまで--------------------------------------------------
function Main(){
	var one = nextIntArray();
	var N = one[0];
	var M = one[1];
	var P = one[2];
	var max = Math.pow(10,15);
	var kyori = new Array(N).fill(max);
	var list = new Array(N);
	var rlist = new Array(N);
	var pok = new Array(N).fill(false);
	var nok = new Array(N).fill(false);
	for(var i = 0; i < N; i++){
		list[i] = {
			child : [],
			access : false
		};
		rlist[i] = {
			child : [],
			access : false
		};
	}
	kyori[0] = 0;
	var e = new Array(M);
	for(var i = 0; i < M; i++){
		var tmp = nextIntArray();
		e[i] = {
			u : tmp[0] - 1,
			v : tmp[1] - 1,
			c : (tmp[2] - P) * (-1)
		}
		list[tmp[0] - 1].child.push(tmp[1] - 1);
		rlist[tmp[1] - 1].child.push(tmp[0] - 1);
	}
	var ok = new Array(N).fill(false);
	dfs(0);
	rdfs(N - 1);
	function dfs(index){
		if(pok[index]){
			return;
		}
		pok[index] = true;
		var child = list[index].child;
		for(var i = 0; i < child.length; i++){
			dfs(child[i]);
		}
	}
	function rdfs(index){
		if(nok[index]){
			return;
		}
		nok[index] = true;
		var child = list[index].child;
		for(var i = 0; i < child.length; i++){
			dfs(child[i]);
		}
	}
	for(var i = 0; i < N; i++){
		ok[i] = pok[i] && nok[i];
	}
	var negative = new Array(N).fill(false);
	for(var i = 0; i < N - 1; i++){
		for(var j = 0; j < M; j++){
			if(kyori[e[j].v] > kyori[e[j].u] + e[j].c){
				kyori[e[j].v] = kyori[e[j].u] + e[j].c;
			}
		}
	}
	for(var i = 0; i < N; i++){
		for(var j = 0; j < M; j++){
			if(!ok[e[j].u]){
				continue;
			}
			if(!ok[e[j].v]){
				continue;
			}
			if(kyori[e[j].v] > kyori[e[j].u] + e[j].c){
				myout(-1);
				return;
			}
		}
	}
	myout(Math.max(kyori[N - 1] * (-1), 0));
}
