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; static class Program{ const int mod=(int)1e9+7; static void Main(){ Sc sc=new Sc(); var s=sc.Ia; var bs=new Bitset[s[0]+1]; bs[0]=new Bitset(s[0]+1,1); for(int i = 1;i<=s[0];i++) { var e=sc.Ia; bs[i]=new Bitset(s[2]+1); for(int j = 0;j=0;i--) { if(bs[s[0]][i]==1){ Console.WriteLine("{0}",s[2]-i); return; } } Console.WriteLine("{0}",-1); } } public class Bitset{ public int n,l; public ulong[] he; public Bitset(int n){ this.n=n; l=(n>>6)+1; he=new ulong[l]; } public Bitset(int n,long a){ this.n=n; l=(n>>6)+1; he=new ulong[l]; he[0]=(ulong)a; } public Bitset(int n,bool b){ this.n=n; l=(n>>6)+1; he=new ulong[l]; int y=n%64; if(y==0){for(int i = 0;i>6]=(he[i>>6]&(ulong.MaxValue^(1UL<>6]>>i)&1);} } public static Bitset operator&(Bitset a,Bitset b){ Bitset c=new Bitset(a.n); int d=Math.Min(a.l,b.l); for(int i=0;ia.l<<6){return c;} int d=(b+63)>>6; if(b%64==0){for(int i=a.l-1;i>=d;i--){c.he[i]=a.he[i-d];}} else{ for(int i=a.l-1;i>=d;i--){c.he[i]=(a.he[i-d+1]<>(64-b));} c.he[d-1]=a.he[0]<>(Bitset a,int b){ Bitset c=new Bitset(a.n); if(b>a.l<<6){return c;} int d=(b+63)>>6; if(b%64==0){for(int i=0;i+d>b)|(a.he[i+d]<<(64-b));} c.he[c.l-d]=a.he[c.l-1]>>b; } return c; } public static bool operator==(Bitset a,Bitset b){ int mx=Max(a.l,b.l),mn=Min(a.l,b.l); for(int i=0;ib.l){for(int i=mn;ib.l){for(int i=mn;is.Length?new string('0',64-s.Length):"")+s; t=s+t; } s=Convert.ToString((long)he[l-1],2); s=((n%64)>s.Length?new string('0',(n%64)-s.Length):"")+s; return s+t; } } 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(int a){return Array.ConvertAll((a.ToString()+" "+Console.ReadLine()).Split(),int.Parse);} public int[] Ia3(bool a,int b,bool c,int d){return Array.ConvertAll(((a?b.ToString()+" ":"")+Console.ReadLine()+(c?" "+d.ToString():"")).Split(),int.Parse);} public long[] La2{get{return Array.ConvertAll(("0 "+Console.ReadLine()+" 0").Split(),long.Parse);}} public long[] La3(int a){return Array.ConvertAll((a.ToString()+" "+Console.ReadLine()).Split(),long.Parse);} public long[] La3(bool a,int b,bool c,int d){return Array.ConvertAll(((a?b.ToString()+" ":"")+Console.ReadLine()+(c?" "+d.ToString():"")).Split(),long.Parse);} public T[] Arr(int n,Func f){var a=new T[n];for(int i=0;i(int n,Func f){var a=new T[n];for(int i=0;i(int n,Func f){var a=new T[n];for(int i=0;i(int n,Func f){var a=new T[n];for(int i=0;i