using System;
using System.Collections.Generic;
using System.Collections;
using System.Collections.Specialized;
using System.Linq;
using System.Text;
using System.IO;
using System.Reflection;
using static System.Math;
using System.Numerics;
using System.Threading;
using System.Runtime.CompilerServices;
using System.Diagnostics;
//using nint=System.Int32;
static class Program{
	const int mod=(int)1e9+7;
	const long inf=long.MaxValue/3;
	static void Main(){
		Sc sc=new Sc();
		var s=sc.Ia;
		var g=new long[s[0]][];
		for(int i = 0;i<s[0];i++) {
			g[i]=Enumerable.Repeat(1L,s[0]).ToArray();
		}
		for(int i = 0;i<s[1];i++) {
			var e=sc.Ia;
			g[e[0]][e[1]]=0;
		}
		var c=Mp(g,g,s[2]-1);
		Console.WriteLine("{0}",s[0]-c[0].Sum());
	}
	static long[][] Mm(long[][] a,long[][] b){
		var q=new long[a.Length][];
		for(int j=0;j<a.Length;j++){
			q[j]=Enumerable.Repeat(inf,b[0].Length).ToArray();
			for(int i=0;i<b[0].Length;i++){
				for(int k=0;k<a.Length;k++){
					q[j][i]=Min(q[j][i],a[j][k]+b[k][i]);
				}
			}
		}
		return q;
	}
	static long[][] Mp(long[][] r,long[][] x,long e){
		while(e>0){
			if((e&1)>0){r=Mm(x,r);}
			x=Mm(x,x);
			e>>=1;
		}
		return r;
	}
}

public class Sc{
	public int I{get{return int.Parse(Console.ReadLine());}}
	public long L{get{return long.Parse(Console.ReadLine());}}
	public double D{get{return double.Parse(Console.ReadLine());}}
	public string S{get{return Console.ReadLine();}}
	public int[] Ia{get{return Array.ConvertAll(Console.ReadLine().Split(),int.Parse);}}
	public long[] La{get{return Array.ConvertAll(Console.ReadLine().Split(),long.Parse);}}
	public double[] Da{get{return Array.ConvertAll(Console.ReadLine().Split(),double.Parse);}}
	public string[] Sa{get{return Console.ReadLine().Split();}}
	public object[] Oa{get{return Console.ReadLine().Split();}}
	public int[] Ia2{get{return Array.ConvertAll(("0 "+Console.ReadLine()+" 0").Split(),int.Parse);}}
	public int[] Ia3(string a,string b){return Array.ConvertAll((a+Console.ReadLine()+b).Split(),int.Parse);}
	public int[] Ia3(int a){return Array.ConvertAll((Console.ReadLine()+" "+a.ToString()).Split(),int.Parse);}
	public long[] La2{get{return Array.ConvertAll(("0 "+Console.ReadLine()+" 0").Split(),long.Parse);}}
	public long[] La3(string a,string b){return Array.ConvertAll((a+Console.ReadLine()+b).Split(),long.Parse);}
	public long[] La3(int a){return Array.ConvertAll((Console.ReadLine()+" "+a.ToString()).Split(),long.Parse);}
	public double[] Da2{get{return Array.ConvertAll(("0 "+Console.ReadLine()+" 0").Split(),double.Parse);}}
	public double[] Da3(string a,string b){return Array.ConvertAll((a+Console.ReadLine()+b).Split(),double.Parse);}
	public T[] Arr<T>(int n,Func<T> f){var a=new T[n];for(int i=0;i<n;i++){a[i]=f();}return a;}
	public T[] Arr<T>(int n,Func<int,T> f){var a=new T[n];for(int i=0;i<n;i++){a[i]=f(i);}return a;}
	public T[] Arr<T>(int n,Func<string[],T> f){var a=new T[n];for(int i=0;i<n;i++){a[i]=f(Console.ReadLine().Split());}return a;}
	public T[] Arr<T>(int n,Func<int,string[],T> f){var a=new T[n];for(int i=0;i<n;i++){a[i]=f(i,Console.ReadLine().Split());}return a;}
	public (T,T) Tp2<T>(){var s=Console.ReadLine().Split();return (Ct<T>(s[0]),Ct<T>(s[1]));}
	public (T,T,T) Tp3<T>(){var s=Console.ReadLine().Split();return (Ct<T>(s[0]),Ct<T>(s[1]),Ct<T>(s[2]));}
	private T Ct<T>(string s){return (T)Convert.ChangeType(s,typeof(T));}
}