Problem: New Year is coming in Tree World! In this world, as the name implies, there are n cities connected by n - 1 roads, and for any two distinct cities there always exists a path between them. The cities are numbered by integers from 1 to n, and the roads are numbered by integers from 1 to n - 1. Let's define d(u, v) as total length of roads on the path between city u and city v.

As an annual event, people in Tree World repairs exactly one road per year. As a result, the length of one road decreases. It is already known that in the i-th year, the length of the ri-th road is going to become wi, which is shorter than its length before. Assume that the current year is year 1.

Three Santas are planning to give presents annually to all the children in Tree World. In order to do that, they need some preparation, so they are going to choose three distinct cities c1, c2, c3 and make exactly one warehouse in each city. The k-th (1 ≤ k ≤ 3) Santa will take charge of the warehouse in city ck.

It is really boring for the three Santas to keep a warehouse alone. So, they decided to build an only-for-Santa network! The cost needed to build this network equals to d(c1, c2) + d(c2, c3) + d(c3, c1) dollars. Santas are too busy to find the best place, so they decided to choose c1, c2, c3 randomly uniformly over all triples of distinct numbers from 1 to n. Santas would like to know the expected value of the cost needed to build the network.

However, as mentioned, each year, the length of exactly one road decreases. So, the Santas want to calculate the expected after each length change. Help them to calculate the value.

Input

The first line contains an integer n (3 ≤ n ≤ 105) — the number of cities in Tree World.

Next n - 1 lines describe the roads. The i-th line of them (1 ≤ i ≤ n - 1) contains three space-separated integers ai, bi, li (1 ≤ ai, bi ≤ n, ai ≠ bi, 1 ≤ li ≤ 103), denoting that the i-th road connects cities ai and bi, and the length of i-th road is li.

The next line contains an integer q (1 ≤ q ≤ 105) — the number of road length changes.

Next q lines describe the length changes. The j-th line of them (1 ≤ j ≤ q) contains two space-separated integers rj, wj (1 ≤ rj ≤ n - 1, 1 ≤ wj ≤ 103). It means that in the j-th repair, the length of the rj-th road becomes wj. It is guaranteed that wj is smaller than the current length of the rj-th road. The same road can be repaired several times.

Output

Output q numbers. For each given change, print a line containing the expected cost needed to build the network in Tree World. The answer will be considered correct if its absolute and relative error doesn't exceed 10 - 6.

Examples

Input

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


Output

14.0000000000
12.0000000000
8.0000000000
6.0000000000
4.0000000000


Input

6
1 5 3
5 3 2
6 1 7
1 4 4
5 2 3
5
1 2
2 1
3 5
4 1
5 2


Output

19.6000000000
18.6000000000
16.6000000000
13.6000000000
12.6000000000

Note

Consider the first sample. There are 6 triples: (1, 2, 3), (1, 3, 2), (2, 1, 3), (2, 3, 1), (3, 1, 2), (3, 2, 1). Because n = 3, the cost needed to build the network is always d(1, 2) + d(2, 3) + d(3, 1) for all the triples. So, the expected cost equals to d(1, 2) + d(2, 3) + d(3, 1).

Solution (in JAVA):

Solution:
import java.io.*;
import java.util.*;
import java.text.*;
import java.lang.*;
import java.math.*;
 
public class Myclass{
	static ArrayList[] a=new ArrayList[200001];
	static long count []=new long [200001];
	static long dp []=new long [200001];
	static boolean visited[]=new boolean [200001];
	static long tot;
	static long f(long a,long b) {
		return ((a*(a-1))/2L)*b;
	}
	static void dfs(int n) {
		visited[n]=true;
		dp[n]++;
		for(int i=0;i<a[n].size();i++) {
			pair id=(pair) a[n].get(i);
			if(!visited[id.x]) {
				dfs(id.x);
				dp[n]+=dp[id.x];
				count[id.y]+=f(dp[id.x],tot-dp[id.x]);
				count[id.y]+=f(tot-dp[id.x],dp[id.x]);
				
			}
		}
	}
    public void solve () {
        InputReader in = new InputReader(System.in);
        PrintWriter pw = new PrintWriter(System.out); 
        tot=in.nextLong();
        int n=(int)tot;
        for(int i=0;i<=n;i++) {
        	a[i]=new ArrayList<pair>();
        }
        long b[]=new  long [n+1];
        for(int i=0;i<n-1;i++) {
        	int x=in.nextInt();
        	int y=in.nextInt();
        	a[x].add(new pair(y,(i+1)));
        	a[y].add(new pair(x,(i+1)));
        	b[i+1]=in.nextLong();
        }
        dfs(1);
        int q=in.nextInt();
        double sum=0.0;
        double got=(tot*(tot-1)*(tot-2))/(6L*1.0);
        	
        for(int i=1;i<=n-1;i++) {
        	sum+=count[i]*b[i]*2.0; 
        }
        while(q-->0) {
        	int id=in.nextInt();
        	long val=in.nextLong();
        	sum-=(count[id]*(b[id]-val)*2.0);
        	b[id]=val;
        	double ans=(sum)/(got*1.0);
        	pw.printf("%.10f\n",ans);
        }
        pw.flush();
        pw.close();
    }
    public static void main(String[] args) throws Exception {
        
        
        new Thread(null,new Runnable() {
            public void run() {
                new Myclass().solve();
            }
        },"1",1<<26).start();
        
        
    }
   
    static void debug(Object... o) {
        System.out.println(Arrays.deepToString(o));
        }
        
        static class InputReader 
        {
        private final InputStream stream;
        private final byte[] buf = new byte[8192];
        private int curChar, snumChars;
        private SpaceCharFilter filter;
 
        public InputReader(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 int[] nextIntArray(int n) 
        {
            int a[] = new int[n];
            for (int i = 0; i < n; i++) 
            {
                a[i] = nextInt();
            }
            return a;
        }
 
        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 String nextLine() 
        {
            int c = snext();
            while (isSpaceChar(c))
                c = snext();
            StringBuilder res = new StringBuilder();
            do 
            {
                res.appendCodePoint(c);
                c = snext();
            } while (!isEndOfLine(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;
        }
 
        private boolean isEndOfLine(int c) 
        {
            return c == '\n' || c == '\r' || c == -1;
        }
 
        public interface SpaceCharFilter
        {
            public boolean isSpaceChar(int ch);
        }
    }
        public static long mod = 1000000007;
        public static int d;
        public static int p;
        public static int q;
        public void extended(int a,int b) {
            if(b==0) {
                d=a;
                p=1;
                q=0;
            }
            else
            {
                extended(b,a%b);
                int temp=p;
                p=q;
                q=temp-(a/b)*q;
            }
        }
        public static int binaryExponentiation(int x,int n)
        {
            int result=1;
            while(n>0)
            {
                if(n % 2 ==1)
                    result=result * x;
                x=x*x;
                n=n/2;
            }
            return result;
        }
        
        public static long binaryExponentiation(long x,long n)
        {
            long result=1;
            while(n>0)
            {
                if(n % 2 ==1)
                    result=result * x;
                x=x*x;
                n=n/2;
            }
            return result;
        }
        
        public static long[] shuffle(long[] a,Random gen)
        {
            int n = a.length;
            for(int i=0;i<n;i++)
            {
                int ind = gen.nextInt(n-i)+i;
                long temp = a[ind];
                a[ind] = a[i];
                a[i] = temp;
            }
            return a;
        }
        
        public static void swap(int a, int b){
            int temp = a;
            a = b;
            b = temp;
        }
        
        public static HashSet<Integer> primeFactorization(int n)
        {
            HashSet<Integer> a =new HashSet<Integer>();
            for(int i=2;i*i<=n;i++)
            {
                while(n%i==0)
                {
                    a.add(i);
                    n/=i;
                }
            }
            if(n!=1)
                a.add(n);
            return a;
        }
        
        public static void sieve(boolean[] isPrime,int n)
        {
            for(int i=1;i<n;i++)
                isPrime[i] = true;
            
            isPrime[0] = false;
            isPrime[1] = false;
            
            for(int i=2;i*i<n;i++)
            {
                if(isPrime[i] == true)
                {
                    for(int j=(2*i);j<n;j+=i)
                        isPrime[j] = false;
                }
            }
        }
        
        public static long GCD(long n,long m)
        {
            if(m==0)
                return n;
            else
                return GCD(m,n%m);
        }
        
        static class pair implements Comparable<pair>
        {
           Integer x,y;
            
            pair(int x,int y)
            {
                this.x=x;
                this.y=y;
            }

            public int compareTo(pair o) {
                int result = x.compareTo(o.x);
                if(result==0)
                    result = y.compareTo(o.y);
                
                return result;
            }  
            
            public String toString()
            {
                return x+" "+y;
            }
            
            public boolean equals(Object o)
            {
                if (o instanceof pair)
                {
                    pair p = (pair)o;
                    return p.x == x && p.y == y ;
                }
                return false;
            }
            
            public int hashCode()
            {
                return new Double(x).hashCode()*31 + new Long(y).hashCode();
            }
        }
        
    
}

/*class dsu{
    int parent[];
    dsu(int n){
        parent=new int[n+1];
        for(int i=0;i<=n;i++)
        {
            parent[i]=i;
        }
    }
    int root(int n) {
        while(parent[n]!=n)
        { 
            parent[n]=parent[parent[n]];
            n=parent[n];
        }
        return n;
    }
    void union(int _a,int _b) {
        int p_a=root(_a);
        int p_b=root(_b);
        
            parent[p_a]=p_b;
        
            
    }
    boolean find(int a,int b) {
        if(root(a)==root(b))
            return true;
        else
            return  false;
    }
    
    
}
/*class Segment{ 
    int seg[]; 
    int a[];
    int lazy[];
    Segment (int n,int b[]){
        seg=new int[4*n];
        lazy=new int[4*n];
        a=new int[b.length];
        a=b.clone();
    }
    public void build(int node,int start,int end) {
        if(start==end) {
            seg[node]=a[start];
            return ;
        }
        int mid=(start+end)/2;
        build(2*node+1,start,mid);
        build(2*node+2,mid+1,end);
        seg[node]=seg[2*node+1]+seg[2*node+2];
    }
    public void update(int node,int start,int end,int id,int val) {
        if(start==end) {
            seg[node]=a[start]=val;
            return;
        }
        int mid=(start+end)/2;
        if(id>=start && id<=mid) {
            update(2*node+1,start,mid,id,val);
        }
        else
            update(2*node+2,mid+1,end,id,val);
        seg[node]=seg[2*node+1]+seg[2*node+2];
    }
    public int query(int node,int start,int end,int l,int r) {
        if(l>end || r<start)
            return 0;
        if(start>=l && end<=r)
            return seg[node];
        
        int  mid=(start+end)/2;
        return (query(2*node+1,start,mid,l,r)+query(2*node+2,mid+1,end,l,r));
    }
    public void updateRange(int node,int start,int end,int l,int r,int val) {
        if(lazy[node]!=0) {
            if(start!=end) {
                lazy[2*node+1]+=lazy[node];
                lazy[2*node+2]+=lazy[node];
            }
            lazy[node]=0;
        }
        if(l>end || r<start)
            return ;
        if(start>=l && end<=r) {
            seg[node]=(end-start+1)*val;
            if(start!=end) {
                lazy[2*node+1]+=val;
                lazy[2*node+2]+=val;
            }
            lazy[node]=0;
            return ;
        }
        int mid=(start+end)/2;
        updateRange(2*node+1,start,mid,l,r,val);
        updateRange(2*node+2,mid+1,end,l,r,val);
        seg[node]=seg[2*node+1]+seg[2*node+2];
    }
    public int queryRange(int node,int start,int end,int l,int r) {
        if(l>end || r<start)
            return 0;
        if(lazy[node]!=0) {
            seg[node]=(end-start+1)*lazy[node];
            if(start!=end) {
                lazy[2*node+1]+=lazy[node];
                lazy[2*node+2]+=lazy[node];
            }
            lazy[node]=0;
        }
        if(start>=l && end<=r)
            return seg[node];
        
        int  mid=(start+end)/2;
        return (query(2*node+1,start,mid,l,r)+query(2*node+2,mid+1,end,l,r));
    }
    
}*/