Problem:
Score : 100 points

Problem Statement

There is a tree with N vertices, numbered 1, 2, \ldots, N.
For each i (1 \leq i \leq N - 1), the i-th edge connects Vertex x_i and y_i.

Taro has decided to paint each vertex in white or black.
Here, it is not allowed to paint two adjacent vertices both in black.

Find the number of ways in which the vertices can be painted, modulo 10^9 + 7.

Constraints

All values in input are integers.

1 \leq N \leq 10^5

1 \leq x_i, y_i \leq N

The given graph is a tree.

Input

Input is given from Standard Input in the following format:

N
x_1 y_1
x_2 y_2
:
x_{N - 1} y_{N - 1}

Output

Print the number of ways in which the vertices can be painted, modulo 10^9 + 7.

Sample Input 1

3
1 2
2 3

Sample Output 1

5

There are five ways to paint the vertices, as follows:

Sample Input 2

4
1 2
1 3
1 4

Sample Output 2

9

There are nine ways to paint the vertices, as follows:

Sample Input 3

1

Sample Output 3

2

Sample Input 4

10
8 5
10 8
6 5
1 5
4 8
2 10
3 6
9 2
1 7

Sample Output 4

157

Solution in Java (OpenJDK 11.0.6) (judge verdict: Accepted)

/*
ID: davidzh8
PROG: subset
LANG: JAVA
 */

import java.io.*;
import java.util.*;
import java.lang.*;

public class Main {

    static long startTime = System.nanoTime();
    static ArrayList<Integer>[] adj;
    static long[][] dp;
    public static void solve() throws Exception {
        boolean debug = (true);
        FastScanner sc = new FastScanner("independentset.in", debug);
        FastWriter pw = new FastWriter("independentset.out", debug);
        int N= sc.ni();
        adj= new ArrayList[N];
        for(int i=0; i<N; i++){
            adj[i]= new ArrayList<>();
        }
        for (int i = 0; i < N-1; i++) {
            int a= sc.ni()-1;
            int b= sc.ni()-1;
            adj[a].add(b);
            adj[b].add(a);
        }
        dp= new long[N][2];
        for (int i = 0; i < N; i++) {
            Arrays.fill(dp[i],1);
        }
        dfs(0,-1);
        pw.println((dp[0][0]+dp[0][1])%MOD);

        long endTime = System.nanoTime();
     //   System.out.println("Execution Time: " + (endTime - startTime) / 1e9 + " s");
        pw.close();
    }
    static int MOD= (int)1e9+7;
    static void dfs(int cur, int par){
        for (int next:adj[cur]) {
            if(next==par) continue;
            dfs(next, cur);
            dp[cur][0]*= dp[next][0]+dp[next][1];
            dp[cur][1]*=dp[next][0];
            dp[cur][0]%=MOD;
            dp[cur][1]%=MOD;
        }
    }


    static class Pair implements Comparable<Pair> {
        int a;
        int b;

        public Pair(int a, int b) {
            this.a = a;
            this.b = b;
        }

        public int compareTo(Pair obj) {
            if (obj.a == a) {
                return b - obj.b;
            } else return a - obj.a;
        }
    }


    static class djset {
        int N;
        int[] parent;

        // Creates a disjoint set of size n (0, 1, ..., n-1)
        public djset(int n) {
            parent = new int[n];
            N = n;
            for (int i = 0; i < n; i++)
                parent[i] = i;
        }

        public int find(int v) {

            // I am the club president!!! (root of the tree)
            if (parent[v] == v) return v;

            // Find my parent's root.
            int res = find(parent[v]);

            // Attach me directly to the root of my tree.
            parent[v] = res;
            return res;
        }

        public boolean union(int v1, int v2) {

            // Find respective roots.
            int rootv1 = find(v1);
            int rootv2 = find(v2);

            // No union done, v1, v2 already together.
            if (rootv1 == rootv2) return false;

            // Attach tree of v2 to tree of v1.
            parent[rootv2] = rootv1;
            return true;
        }


    }

    static class FastScanner {
        InputStream dis;
        byte[] buffer = new byte[1 << 17];
        int pointer = 0;

        public FastScanner(String fileName, boolean debug) throws Exception {
            if (debug) dis = System.in;
            else dis = new FileInputStream(fileName);
        }

        int ni() throws Exception {
            int ret = 0;

            byte b;
            do {
                b = nextByte();
            } while (b <= ' ');
            boolean negative = false;
            if (b == '-') {
                negative = true;
                b = nextByte();
            }
            while (b >= '0' && b <= '9') {
                ret = 10 * ret + b - '0';
                b = nextByte();
            }

            return (negative) ? -ret : ret;
        }

        long nl() throws Exception {
            long ret = 0;

            byte b;
            do {
                b = nextByte();
            } while (b <= ' ');
            boolean negative = false;
            if (b == '-') {
                negative = true;
                b = nextByte();
            }
            while (b >= '0' && b <= '9') {
                ret = 10 * ret + b - '0';
                b = nextByte();
            }

            return (negative) ? -ret : ret;
        }

        byte nextByte() throws Exception {
            if (pointer == buffer.length) {
                dis.read(buffer, 0, buffer.length);
                pointer = 0;
            }
            return buffer[pointer++];
        }

        String next() throws Exception {
            StringBuffer ret = new StringBuffer();

            byte b;
            do {
                b = nextByte();
            } while (b <= ' ');
            while (b > ' ') {
                ret.appendCodePoint(b);
                b = nextByte();
            }

            return ret.toString();
        }
    }

    static class FastWriter {
        public PrintWriter pw;

        public FastWriter(String name, boolean debug) throws IOException {
            if (debug) {
                pw = new PrintWriter(System.out);
            } else {
                pw = new PrintWriter(new BufferedWriter(new FileWriter(new File(name))));
            }
        }

        public void println(Object text) {
            pw.println(text);
        }

        public void print(Object text) {
            pw.print(text);
        }

        public void close() {
            pw.close();
        }

        public void flush() {
            pw.flush();
        }
    }

    public static void main(String[] args) throws Exception {
        Thread thread = new Thread(null, () -> {
            try {
                solve();
            } catch (Exception e) {
                e.printStackTrace();
            }
        }, "", 1 << 28);
        thread.start();
        thread.join();
    }

}