Problem: You are given array a with n integers and m queries. The i-th query is given with three integers li, ri, xi.

For the i-th query find any position pi (li ≤ pi ≤ ri) so that api ≠ xi.

Input

The first line contains two integers n, m (1 ≤ n, m ≤ 2·105) — the number of elements in a and the number of queries.

The second line contains n integers ai (1 ≤ ai ≤ 106) — the elements of the array a.

Each of the next m lines contains three integers li, ri, xi (1 ≤ li ≤ ri ≤ n, 1 ≤ xi ≤ 106) — the parameters of the i-th query.

Output

Print m lines. On the i-th line print integer pi — the position of any number not equal to xi in segment [li, ri] or the value  - 1 if there is no such number.

Examples

Input

6 4
1 2 1 1 3 5
1 4 1
2 6 2
3 4 1
3 4 2


Output

2
6
-1
4

Solution (in JAVA):

Solution:
import java.awt.Point;
import java.awt.geom.Line2D;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileReader;
import java.io.OutputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.security.GuardedObject;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.Comparator;
import java.util.HashMap;
import java.util.HashSet;
import java.util.InputMismatchException;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;
import java.util.PriorityQueue;
import java.util.Queue;
import java.util.Random;
import java.util.Scanner;
import java.util.Stack;
import java.util.StringTokenizer;
import java.util.TreeMap;
import java.util.TreeSet;
import java.io.InputStream;
import java.math.BigInteger;






/**
 * Built using CHelper plug-in
 * Actual solution is at the top
 */

public class Main {
    public static void main(String[] args) throws IOException {
        InputStream inputStream = System.in;
        
        OutputStream outputStream = System.out;
        FastScanner in;
        PrintWriter out;
        
           in=new FastScanner(System.in);
            out=new PrintWriter(System.out);
        //in=new FastScanner(new FileInputStream(new File("C://Users//KANDARP//Desktop//coding_contest_creation (1).txt")));
        
        TaskC solver = new TaskC();
        long var=System.currentTimeMillis();
        solver.solve(1, in, out);
        /*if(System.getProperty("ONLINE_JUDGE")==null){
            out.println("["+(double)(System.currentTimeMillis()-var)/1000+"]");
        }*/
        out.close();
    }
}
class Pair {
	
    long x,y,index;
    long  r1,r2;
    HashMap<Double,Long> map=new HashMap<>();
    Pair(long x,long y,int index){
        this.x=x;
        this.y=y;
        this.index=index;
    }
    public String toString(){
        return this.x+" "+this.y+" ";
    }
    
}
class tupple{
    long x,y,z;
    ArrayList<String> list=new ArrayList<>();
    tupple(long x,long y,long z){
        this.x=x;
        this.y=y;
        this.z=z;
    }
    tupple(tupple cl){
        this.x=cl.x;
        this.y=cl.y;
        this.z=cl.z;
        this.list=cl.list;
    }
}
class Edge implements  Comparable<Edge>{
    int u;
    int v;
    int time;
    long cost;
    long wcost;
    public Edge(int u,int v,long cost,long wcost){
        this.u=u;
        this.v=v;
        this.cost=cost;
        this.wcost=wcost;
        time=Integer.MAX_VALUE;
    }
    public int other(int x){
        if(u==x)return v;
        return u;
    }
    @Override
    public int compareTo(Edge o) {
        // TODO Auto-generated method stub
        return Long.compare(cost, o.cost);
    }
}
class Ss{
    Integer a[]=new Integer[3];
    Ss(Integer a[]){
        this.a=a;
        
    }
    public int hashCode(){
        return a[0].hashCode()+a[1].hashCode()+a[2].hashCode();
    }
    public boolean equals(Object o){
        Ss x=(Ss)o;
        for(int i=0;i<3;i++){
            if(x.a[i]!=this.a[i]){
                return false;
            }
        }
        return true;
        
    }
}
class queary{
    int type;
    int l;
    int r;
    int index;
    queary(int type,int l,int r){
        this.type=type;
        this.l=l;
        this.r=r;
    }
}
class boat implements Comparable<boat>{
    int capacity;
    int index;
    boat(int capacity,int index)
    {
        this.capacity=capacity;
        this.index=index;
    }
    @Override
    public int compareTo(boat o) {
        // TODO Auto-generated method stub
        return this.capacity-o.capacity;
    }
}
class angle{
    double x,y,angle;
    int index;
    angle(int x,int y,double angle){
        this.x=x;
        this.y=y;
        this.angle=angle;
    }
}
class TaskC {
    static long mod=1000000007;
//    SegTree tree;
    //    int min[];
 /*   static int prime_len=1000010;
    static int prime[]=new int[prime_len];
    static long n_prime[]=new long[prime_len];
    static ArrayList<Integer> primes=new ArrayList<>();
    static{ 
        for(int i=2;i<=Math.sqrt(prime.length);i++){
            for(int j=i*i;j<prime.length;j+=i){
                
                prime[j]=i;
                
            }
        }
        for(int i=2;i<prime.length;i++){
            n_prime[i]=n_prime[i-1];
            if(prime[i]==0){
               n_prime[i]++;
            }
            
        }
    //  System.out.println("end");
        
    //  prime[0]=true;
    //  prime[1]=1;
    }
    /*
     *  long pp[]=new long[10000001];
            pp[0]=0;
            pp[1]=1;
            for(int i=2;i<pp.length;i++){
                if(prime[i]!=0){
                    int gcd=(int)greatestCommonDivisor(i/prime[i], prime[i]);
                    pp[i]=(pp[i/prime[i]]*pp[prime[i]]*gcd)/pp[(int)gcd];
                }
                else
                    pp[i]=i-1;
            }
        

}
     * */
    class Rmq {

		  int[] logTable;
		  int[][] rmq;
		  int[] a;

		  public Rmq(int[] a) {
		    this.a = a;
		    int n = a.length;

		    logTable = new int[n + 1];
		    for (int i = 2; i <= n; i++)
		      logTable[i] = logTable[i >> 1] + 1;

		    rmq = new int[logTable[n] + 1][n];

		    for (int i = 0; i < n; ++i)
		      rmq[0][i] = i;

		    for (int k = 1; (1 << k) < n; ++k) {
		      for (int i = 0; i + (1 << k) <= n; i++) {
		        int x = rmq[k - 1][i];
		        int y = rmq[k - 1][i + (1 << k - 1)];
		        rmq[k][i] = a[x] <= a[y] ? x : y;
		      }
		    }
		  }

		  public int minPos(int i, int j) {
		    int k = logTable[j - i];
		    int x = rmq[k][i];
		    int y = rmq[k][j - (1 << k) + 1];
		    return a[x] <= a[y] ? a[x] : a[y];
		  }

	}
    	

	
   public void solve(int testNumber, FastScanner in, PrintWriter out) throws IOException {
	 int n=in.nextInt();
	 int m=in.nextInt();
	 int a[]=new int[n];
	 int dp[]=new int[n];
	 for(int i=0;i<n;i++){
		 a[i]=in.nextInt();
	 }
	 dp[0]=-1;
	 for(int i=1;i<n;i++){
		 if(a[i]!=a[i-1]){
			 dp[i]=i-1;
		 }
		 else{
			 dp[i]=dp[i-1];
		 }
	 }
	 for(int i=0;i<m;i++){
		 int l=in.nextInt()-1;
		 int r=in.nextInt()-1;
		 int x=in.nextInt();
		 if(a[r]!=x){
			 out.println(r+1);
		 }
		 else{
			 if(dp[r]>=l){
				 out.println(dp[r]+1);
			 }
			 else{
				 out.println(-1);
			 }
		 }
	 }
   }
   
   static long greatestCommonDivisor (long m, long n){
       long x;
       long y;
       while(m%n != 0){
           x = n;
           y = m%n;
           m = x;
           n = y;
       }
       return n;
   }

 }
	   		   
    /*
     * 	   long res[]=new long[m];
    	   int cl=1;
    	   int cr=0;
    	   for(int i=0;i<m;i++){
    		   int l=(int)q[i].x;
    		   int r=(int)q[i].y;
    		   while(cl>l){
    			   cl--;
    			   ans+=add(cl);
    			   
    		   }
    		   while(cl<l){
    			   ans-=remove(cl);
    			   cl++;
    			  
    		   }
    		   while(cr>r){
    			   ans-=remove(cr);
    			   cr--;
    		   }
    		   while(cr<r){
    			   cr++;
    			   ans+=add(cr);
    		   }
    		   res[(int)q[i].index]=ans;
    	   }
    	   for(int i=0;i<m;i++)
    		   out.println(res[i]);	         
     */
	   	 class SegmentTree2D {
          public  long max(int[][] t, int x1, int y1, int x2, int y2) {
            int n = t.length >> 1;
            x1 += n;
            x2 += n;
            int m = t[0].length >> 1;
            y1 += m;
            y2 += m;
            long res = 0;
            for (int lx = x1, rx = x2; lx <= rx; lx = (lx + 1) >> 1, rx = (rx - 1) >> 1)
              for (int ly = y1, ry = y2; ly <= ry; ly = (ly + 1) >> 1, ry = (ry - 1) >> 1) {
                if ((lx & 1) != 0 && (ly & 1) != 0) res = (res+ t[lx][ly]);
                if ((lx & 1) != 0 && (ry & 1) == 0) res = (res+ t[lx][ry]);
                if ((rx & 1) == 0 && (ly & 1) != 0) res =(res+t[rx][ly]);
                if ((rx & 1) == 0 && (ry & 1) == 0) res = (res+ t[rx][ry]);
              }
            return res;
          }

          public  void add(int[][] t, int x, int y, int value) {
            x += t.length >> 1;
            y += t[0].length >> 1;
            t[x][y] += value;
            for (int tx = x; tx > 0; tx >>= 1)
              for (int ty = y; ty > 0; ty >>= 1) {
                if (tx > 1) t[tx >> 1][ty] = (t[tx][ty]+t[tx ^ 1][ty]);
                if (ty > 1) t[tx][ty >> 1] = (t[tx][ty]+ t[tx][ty ^ 1]);
              }

//          for (int ty = y; ty > 1; ty >>= 1)
//            t[x][ty >> 1] = Math.max(t[x][ty], t[x][ty ^ 1]);
//          for (int tx = x; tx > 1; tx >>= 1)
//            for (int ty = y; ty > 0; ty >>= 1)
//              t[tx >> 1][ty] = Math.max(t[tx][ty], t[tx ^ 1][ty]);

//          for (int lx=x; lx> 0; lx >>= 1) {
//            if (lx > 1)
//              t[lx >> 1][y] = Math.max(t[lx][y], t[lx ^ 1][y]);
//            for (int ly = y; ly > 1; ly >>= 1)
//              t[lx][ly >> 1] = Math.max(t[lx][ly], t[lx][ly ^ 1]);
//          }
          }
    }
     class SegmentTree {

          // Modify the following 5 methods to implement your custom operations on the tree.
          // This example implements Add/Max operations. Operations like Add/Sum, Set/Max can also be implemented.
          long modifyOperation(long x, long y) {
            return  y;
          }

          // query (or combine) operation
          long queryOperation(long leftValue, long rightValue) {
            return (leftValue| rightValue);
          }

          long deltaEffectOnSegment(long delta, long segmentLength) {
            // Here you must write a fast equivalent of following slow code:
            // int result = delta;
            // for (int i = 1; i < segmentLength; i++) result = queryOperation(result, delta);
            // return result;
            return delta;
          }

          int getNeutralDelta() {
            return 0;
          }

          int getInitValue() {
            return 0;
          }

          // generic code
          int n;
          long[] value;
          long[] delta; // delta[i] affects value[i], delta[2*i+1] and delta[2*i+2]

          long joinValueWithDelta(long value, long delta) {
            if (delta == getNeutralDelta()) return value;
            return modifyOperation(value, delta);
          }

          long joinDeltas(long delta1, long delta2) {
            if (delta1 == getNeutralDelta()) return delta2;
            if (delta2 == getNeutralDelta()) return delta1;
            return modifyOperation(delta1, delta2);
          }

          void pushDelta(int root, int left, int right) {
            value[root] = joinValueWithDelta(value[root], deltaEffectOnSegment(delta[root], right - left + 1));
            delta[2 * root + 1] = joinDeltas(delta[2 * root + 1], delta[root]);
            delta[2 * root + 2] = joinDeltas(delta[2 * root + 2], delta[root]);
            delta[root] = getNeutralDelta();
          }

          public SegmentTree(int n) {
            this.n = n;
            value = new long[4 * n];
            delta = new long[4 * n];
            init(0, 0, n - 1);
          }

          void init(int root, int left, int right) {
            if (left == right) {
              value[root] = getInitValue();
              delta[root] = getNeutralDelta();
            } else {
              int mid = (left + right) >> 1;
              init(2 * root + 1, left, mid);
              init(2 * root + 2, mid + 1, right);
              value[root] = queryOperation(value[2 * root + 1], value[2 * root + 2]);
              delta[root] = getNeutralDelta();
            }
          }

          public long query(int from, int to) {
            return query(from, to, 0, 0, n - 1);
          }

          long query(int from, int to, int root, int left, int right) {
            if (from == left && to == right)
              return joinValueWithDelta(value[root], deltaEffectOnSegment(delta[root], right - left + 1));
            pushDelta(root, left, right);
            int mid = (left + right) >> 1;
            if (from <= mid && to > mid)
              return queryOperation(
                  query(from, Math.min(to, mid), root * 2 + 1, left, mid),
                  query(Math.max(from, mid + 1), to, root * 2 + 2, mid + 1, right));
            else if (from <= mid)
              return query(from, Math.min(to, mid), root * 2 + 1, left, mid);
            else if (to > mid)
              return query(Math.max(from, mid + 1), to, root * 2 + 2, mid + 1, right);
            else
              throw new RuntimeException("Incorrect query from " + from + " to " + to);
          }

          public void modify(int from, int to, long delta) {
            modify(from, to, delta, 0, 0, n - 1);
          }

          void modify(int from, int to, long delta, int root, int left, int right) {
            if (from == left && to == right) {
              this.delta[root] = joinDeltas(this.delta[root], delta);
              return;
            }
            pushDelta(root, left, right);
            int mid = (left + right) >> 1;
            if (from <= mid)
              modify(from, Math.min(to, mid), delta, 2 * root + 1, left, mid);
            if (to > mid)
              modify(Math.max(from, mid + 1), to, delta, 2 * root + 2, mid + 1, right);
            value[root] = queryOperation(
                joinValueWithDelta(value[2 * root + 1], deltaEffectOnSegment(this.delta[2 * root + 1], mid - left + 1)),
                joinValueWithDelta(value[2 * root + 2], deltaEffectOnSegment(this.delta[2 * root + 2], right - mid)));
          }
    }

 	
 
    class LcaSparseTable {

          int len;
          int[][] up;
          int[][] max;
          int[] tin;
          int[] tout;
          int time;
          int []lvel;
          
          void dfs(List<Integer>[] tree, int u, int p) {
            tin[u] = time++;
            lvel[u]=lvel[p]+1;
            up[0][u] = p;
            if(u!=p)
            //max[0][u]=weight(u,p);
            for (int i = 1; i < len; i++)
              {
                up[i][u] = up[i - 1][up[i - 1][u]];
                max[i][u]=Math.max(max[i-1][u],max[i-1][up[i-1][u]]);
              }
            for (int v : tree[u])
              if (v != p)
                dfs(tree, v, u);
            tout[u] = time++;
          }

          public LcaSparseTable(List<Integer>[] tree, int root) {
            int n = tree.length;
            len = 1;
            while ((1 << len) <= n) ++len;
            up = new int[len][n];
            max=new int[len][n];
            tin = new int[n];
            tout = new int[n];
            lvel=new int[n];
            lvel[root]=0;
            dfs(tree, root, root);
          }

          boolean isParent(int parent, int child) {
            return tin[parent] <= tin[child] && tout[child] <= tout[parent];
          }

          public int lca(int a, int b) {
            if (isParent(a, b))
              return a;
            if (isParent(b, a))
              return b;
            for (int i = len - 1; i >= 0; i--)
              if (!isParent(up[i][a], b))
                a = up[i][a];
            return up[0][a];
          }
          public long max(int a,int b){
              int lca=lca(a,b);
        //    System.out.println("LCA "+lca);
              long ans=0;
              int h=lvel[a]-lvel[lca];
            //  System.out.println("Height "+h);
              int index=0;
              while(h!=0){
                  if(h%2==1){
                      ans=Math.max(ans,max[index][a]);
                      a=up[index][a];
                  }
                  h/=2;
                  index++;
              }
              h=lvel[b]-lvel[lca];
             // System.out.println("Height "+h);
              
              index=0;
              while(h!=0){ 
                  if(h%2==1){
                      ans=Math.max(ans,max[index][b]);
                      b=up[index][b];
                  }
                  h/=2;
                  index++;
              }
              return ans;
          }
          
    
    static void dfs(List<Integer>[] graph, boolean[] used, List<Integer> res, int u,int parent,List<Integer> collection) {
        
        used[u] = true;
        Integer uu=new Integer(u);
        collection.add(uu);
        for (int v : graph[u]){
          if (!used[v]){
            dfs(graph, used, res, v,u,collection);
            
          }
          else if(collection.contains(v)){
              System.out.println("Impossible");
              System.exit(0);
          }
        }
        collection.remove(uu);
        res.add(u);
      }
        
      public static List<Integer> topologicalSort(List<Integer>[] graph) {
        int n = graph.length;
        boolean[] used = new boolean[n];
        List<Integer> res = new ArrayList<>();
        for (int i = 0; i < n; i++)
          if (!used[i])
            dfs(graph, used, res, i,-1,new ArrayList<Integer>());
        Collections.reverse(res);
        return res;
      }     
  		
 
    static class pairs{
                String company,color;
                String type;
                boolean visit=false;
                pairs(String company,String color,String type){
                    this.company=company;
                    this.color=color;
                    this.type=type;
                }
            }
        
            static void dfs1(List<Integer>[] graph, boolean[] used, List<Integer> res, int u) {
            used[u] = true;
            for (int v : graph[u])
              if (!used[v])
                dfs1(graph, used, res, v);
            res.add(u);
          }

          public static List<Integer> topologicalSort1(List<Integer>[] graph) {
            int n = graph.length;
            boolean[] used = new boolean[n];
            List<Integer> res = new ArrayList<>();
            for (int i = n-1; i >0; i--)
              if (!used[i])
                dfs1(graph, used, res, i);
            Collections.reverse(res);
            return res;
          }
        
        public static long[][] mulmatrix(long m1[][],long m2[][],long mod){
            long ans[][]=new long[m1.length][m2[0].length];
            for(int i=0;i<m1.length;i++){
                for(int j=0;j<m2[0].length;j++){
                    for(int k=0;k<m1.length;k++){
                        ans[i][j]+=(m1[i][k]*m2[k][j]);
                        ans[i][j]%=mod;
                    }
                }
            }
            return ans;
        }
        public static long[][] matrixexpo(long m[][],String n,long mod){
            if(n.equals("1")){
                return m.clone(); 
            }
            if(n.equals("10")){
                return mulmatrix(m, m , mod);
            }
            else{
                long temp [][]=matrixexpo(m,n.substring(0,n.length()-1),mod);
                temp=mulmatrix(temp, temp, mod);
                if(n.charAt(n.length()-1)=='0')return temp;
                else return mulmatrix(temp, m,mod);
            }
        }
        public static boolean isCompatible(long x[],long y[]){
            
            for(int i=0;i<x.length-1;i++){
                if(x[i]==y[i] && x[i+1]==y[i+1] && x[i]==x[i+1] && y[i]==y[i+1]){
                    return false;
                }
            }
            return true;
        }
        
        int phi(int n) {
            int res = n;
            for (int i = 2; i * i <= n; ++i) {
                if (n % i == 0) {
                    while (n % i == 0) {
                        n /= i;
                    }
                    res -= res / i;
                }
            }
            if (n != 1) {
                res -= res / n;
            }
            return res;
        }
        long pow(long x,long y,long mod){
            if(y<=0){
                return 1;
            }
            if(y==1){
                return x%mod;
            }
            long temp=pow(x,y/2,mod);
            if(y%2==0){
                return (temp*temp)%mod;
            }
            else{
                return (((temp*temp)%mod)*x)%mod;
            }
        }
        
/*      long DP(int id,int mask){
            //System.out.println("hi"+dp[id][mask]+" "+id+" "+Integer.toBinaryString(mask));
            if(id==0 && mask==0){
                dp[0][mask]=1;
                return 1;
            }
            else if(id==0){
                dp[0][mask]=0;
                return 0;
            }
            if(dp[id][mask]!=-1){
            
                return dp[id][mask];
            }
            long ans=0;
            for(int i=0;i<n;i++){
                if((mask & (1<<i))!=0 && c[i][id]>=1){
                        ans+=DP(id-1,mask ^ (1 << i));
                        ans%=mod;
                }
            }
            ans+=DP(id-1,mask);
            ans%=mod;
            dp[id][mask]=ans;
            return ans;
        }*/
                long no_of_primes(long m,long n,long k){
                    long count=0,i,j;
                    int primes []=new int[(int)(n-m+2)];
                       if(m==1)    primes[0] = 1;
                        for(i=2; i<=Math.sqrt(n); i++)
                        {
                            j = (m/i);    j *= i;
                            if(j<m)
                                j+=i;
                            for(; j<=n; j+=i)
                             {
                                 if(j!=i)
                                    primes[(int)(j-m)] = 1;
                             }
                        }

                for(i=0; i<=n-m; i++)
                            if(primes[(int)i]==0 && (i-1)%k==0)
                                count++;
                return count;
                }
}
class SegTree {
    int n;
    long  t[];
    long mod=(long)(1000000007);
    SegTree(int n,long  t[]){
        this.n=n;
        this.t=t;
        build();
    }
    
    void build() {  // build the tree
        
        for (int i = n - 1; i > 0; --i)
            t[i]=(t[i<<1]|t[i<<1|1]);
    }

     void modify(int p, long value) {  // set value at position p
      for (t[p += n]+=value; p > 1; p >>= 1) t[p>>1] = (t[p]|t[p^1]);
    }

     long query(int l, int r) {  // sum on interval [l, r)
      long res=0;
              
      for (l += n, r += n; l < r; l >>= 1, r >>= 1) {
            if ((l&1)!=0) res=Math.max(res,t[l++]);
            if ((r&1)!=0) res=Math.max(res,t[--r]);
          }
      return res;
    }

    
    //  
//  
//  
}
class FastScanner
{

    private InputStream stream;
    private byte[] buf = new byte[8192];
    private int curChar;
    private int snumChars;
    private SpaceCharFilter filter;

    public FastScanner(InputStream stream) {
        this.stream = stream;
    }
    
    public int snext() {
        if (snumChars == -1)
            throw new InputMismatchException();
        if (curChar >= snumChars) {
            curChar = 0;
            try {
                snumChars = stream.read(buf);
            } catch (IOException e) {
                throw new InputMismatchException();
            }
            if (snumChars <= 0)
                return -1;
        }
        return buf[curChar++];
    }
    public int nextInt() {
        int c = snext();
        while (isSpaceChar(c))
            c = snext();
        int sgn = 1;
        if (c == '-') {
            sgn = -1;
            c = snext();
        }

        int res = 0;

        do {
            if (c < '0' || c > '9')
                throw new InputMismatchException();
            res *= 10;
            res += c - '0';
            c = snext();
        } while (!isSpaceChar(c));

        return res * sgn;
    }
    
    public long nextLong() {
        int c = snext();
        while (isSpaceChar(c))
            c = snext();
        int sgn = 1;
        if (c == '-') {
            sgn = -1;
            c = snext();
        }

        long res = 0;

        do {
            if (c < '0' || c > '9')
                throw new InputMismatchException();
            res *= 10;
            res += c - '0';
            c = snext();
        } while (!isSpaceChar(c));

        return res * sgn;
    }
    
    public String readString() {
        int c = snext();
        while (isSpaceChar(c))
            c = snext();
        StringBuilder res = new StringBuilder();
        do {
            res.appendCodePoint(c);
            c = snext();
        } while (!isSpaceChar(c));
        return res.toString();
    }

    public boolean isSpaceChar(int c) {
        if (filter != null)
            return filter.isSpaceChar(c);
        return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
    }

    public interface SpaceCharFilter {
        public boolean isSpaceChar(int ch);
    }
}
 class UF {

    private int[] parent;  // parent[i] = parent of i
    private byte[] rank;   // rank[i] = rank of subtree rooted at i (never more than 31)
    private int count;     // number of components
    public UF(int N) {
        if (N < 0) throw new IllegalArgumentException();
        count = N;
        parent = new int[N];
        rank = new byte[N];
        for (int i = 0; i < N; i++) {
            parent[i] = i;
            rank[i] = 0;
        }
    }

    public int find(int p) {
        if (p < 0 || p >= parent.length) throw new IndexOutOfBoundsException();
        while (p != parent[p]) {
            parent[p] = parent[parent[p]];    // path compression by halving
            p = parent[p];
        }
        return p;
    }
    public int count() {
        return count;
    }

    public boolean connected(int p, int q) {
        return find(p) == find(q);
    }

    public boolean union(int p, int q) {
        int rootP = find(p);
        int rootQ = find(q);
        if (rootP == rootQ) return false;

        // make root of smaller rank point to root of larger rank
        if      (rank[rootP] < rank[rootQ]) parent[rootP] = rootQ;
        else if (rank[rootP] > rank[rootQ]) parent[rootQ] = rootP;
        else {
            parent[rootQ] = rootP;
            rank[rootP]++;
        }
        count--;
        return true;
    }
    



}
 class MyArrayList {
	 
    private int[] myStore;
    private int actSize = 0;
     
    public MyArrayList(){
        myStore = new int[2];
    }
     
    public int get(int index){
        if(index < actSize)
            return myStore[index];
         else 
            throw new ArrayIndexOutOfBoundsException();
    }
     
    public void add(int obj){
        if(myStore.length-actSize <= 1)
            increaseListSize();
        myStore[actSize++] = obj;
    }
   
    public int size(){
        return actSize;
    }
     
    private void increaseListSize(){
        myStore = Arrays.copyOf(myStore, myStore.length*2);
    }
}