Go: package main

import (
	"bufio"
	"container/list"
	"os"
	"strconv"
	"fmt"
)

const (
	MAX = 100000
	NIL = -1
)

var (
	n     int
	G     [MAX][]int
	color [MAX]int
)

func DFS(r int, c int) {
	S := list.New()
	S.PushFront(r)
	color[r] = c
	for S.Len() != 0 {
		u := S.Remove(S.Front()).(int)
		for i := 0; i < len(G[u]); i++ {
			v := G[u][i]
			if color[v] == NIL {
				color[v] = c
				S.PushFront(v)
			}
		}
	}
}

func assignColor() {
	id := 1
	for i := 0; i < n; i++ {
		color[i] = NIL
	}
	for i := 0; i < n; i++ {
		if color[i] == NIL {
			id++
			DFS(i, id)
		}
	}
}

func main() {
	var s, t, m, q int
	scanner := bufio.NewScanner(os.Stdin)
	scanner.Split(bufio.ScanWords)
	scanner.Scan()
	n, _ = strconv.Atoi(scanner.Text())
	scanner.Scan()
	m, _ = strconv.Atoi(scanner.Text())
	for i := 0; i < m; i++ {
		scanner.Scan()
		s, _ = strconv.Atoi(scanner.Text())
		scanner.Scan()
		t, _ = strconv.Atoi(scanner.Text())
		if i == 0 {
			G[s] = make([]int, 0)
			G[t] = make([]int, 0)
		}
		G[s] = append(G[s], t)
		G[t] = append(G[t], s)
	}

	assignColor()
	scanner.Scan()
	q, _ = strconv.Atoi(scanner.Text())
	for i := 0; i < q; i++ {
		scanner.Scan()
		s, _ = strconv.Atoi(scanner.Text())
		scanner.Scan()
		t, _ = strconv.Atoi(scanner.Text())
		if color[s] == color[t] {
			fmt.Println("yes")
		} else {
			fmt.Println("no")
		}
	}
}

Python: # -*- coding: utf_8 -*-
import copy

level = False
def debug(v):
    if level:
        print(v)

NOT_FOUND = 0
ENQUEUED = 1
FOUND = 2

def dfs(graph, start, end):
    stack = [start]
    status = [NOT_FOUND] * len(graph)

    def loop(stack, status, graph, start, end):
        debug("-------------------")
        debug(stack)
        debug(graph)
        if len(stack) == 0:
            debug(stack)
            return False

        v = stack.pop()
        status[v] = FOUND
        if v == end:
            return True

        edges = graph[v]
        if len(edges) != 0:
            stack.append(v)
            e = edges.pop(0)
            if e == end:
                return True
            if status[e] == NOT_FOUND:
                stack.append(e)
                status[e] = ENQUEUED

        return loop(stack, status, graph, start, end)

    return loop(stack, status, copy.deepcopy(graph), start, end)

def bfs(graph, start, target):
    debug(graph)
    if start == target:
        return True
    
    queue = []
    status = [NOT_FOUND] * len(graph)
    queue.append(start)

    while len(queue) != 0:
        node = queue.pop(0)
        status[node] = FOUND
        edges = graph[node]
        for e in edges:
            if e == target:
                return True
            if status[e] == NOT_FOUND:
                status[e] = ENQUEUED
                queue.append(e)

    return False

if __name__ == "__main__":
    n, m = [int(x) for x in input().split()]

    g = [[] for i in range(n)]
    for i in range(m):
        u, e = [int(x) for x in input().split()]
        g[u].append(e)
        g[e].append(u)

    n = int(input())
    for i in range(n):
        s, d = [int(x) for x in input().split()]
        if dfs(g, s, d):
            print("yes")
        else:
            print("no")

Python: # -*- coding: utf-8 -*-

def assignColor():
    C = [-1 for i in range(n)]
    for i in range(n):
        if C[i] == -1:
            C = BFS(G, i, C)
    return C

#@profile
def BFS(G, start, C):
    n = len(G)
    Q = [start]
    C[start] = start

    while len(Q) != 0:
        u = Q.pop(0)
        v = [i for i in G[u] if C[i] == -1] # v := ??£??\???????????????????????¢?´¢??????????????????
        
        for i in v:
            Q.append(i)
            C[i] = C[start]
    
    return C

def main():
    
    for i in range(m):
        s, t = list(map(int, input().split()))
        G[s].append(t)
        G[t].append(s)

    C = assignColor()
        
    q = int(input())
    
    for i in range(q):
        s, t = list(map(int, input().split()))
        if C[s] == C[t]:
            print("yes")
        else:
            print("no")
            
if __name__ == "__main__":
    n, m = list(map(int, input().split()))
    G = [[] for i in range(n)]

    main()

Python: from sys import stdin
n, m = map(int, stdin.readline().split())
G = [-1] * n
def root(x):
    if G[x] < 0: return x
    G[x] = root(G[x])
    return G[x]
def uniteSet(x, y):
    x = root(x)
    y = root(y)
    if x == y : return
    if G[x] > G[y] : x, y = y, x
    G[y] = x
for i in range(0, m):
    s, t = map(int, stdin.readline().split())
    uniteSet(s, t)
q = int(stdin.readline())
for i in range(0, q):
    s, t = map(int, stdin.readline().split())
    print("yes" if root(s) == root(t) else "no")

Python: from sys import stdin
n, m = map(int, stdin.readline().split())
G = [-1] * n
def root(x):
    if G[x] < 0: return x
    G[x] = root(G[x])
    return G[x]
def uniteSet(x, y):
    x = root(x)
    y = root(y)
    if x == y : return
    if G[x] > G[y] : x, y = y, x
    G[y] = x
findSet = lambda x, y: root(x) == root(y)
for i in range(0, m):
    s, t = map(int, stdin.readline().split())
    uniteSet(s, t)
q = int(stdin.readline())
for i in range(0, q):
    s, t = map(int, stdin.readline().split())
    print("yes" if findSet(s, t) else "no")

Python: #coding: utf-8
global b

n, m = map(int,input().split())
List = [[] for i in range(n)]

for i in range(m):
    s,t = map(int,input().split())
    List[s].append(t)
    List[t].append(s)


def search(a,target):
    if a == target:
        print("yes")
        return False
    for member in List[a]:
        if color[member] == "white":
            color[member] = "black"
            if search(member, target) == False:
                return False
    return True
            
p = int(input())
for i in range(p):
    color = ["white" for i in range(n)]
    a, target = map(int,input().split())
    color[a] = "black"
    b = search(a, target)
    if b :
        print("no")

Python: from collections import deque

def bfs(graph, start, goal, connection):
    visited = {start: None}
    unvisited = deque()
    unvisited.append(start)
    while unvisited:
        now = unvisited.popleft()
        if now == goal or goal in connection[now]:
            connection[start].add(goal)
            connection[goal].add(start)
            return "yes"
        for next in graph[now]:
            if not (next in visited):
                unvisited.append(next)
                visited[next] = now
    return "no"

n, m = map(int, input().split())
g = [[] for i in range(n)]
c = [set() for i in range(n)]

for i in range(m):
    inp = list(map(int, input().split()))
    g[inp[0]].append(inp[1])
    g[inp[1]].append(inp[0])
    c[inp[0]].add(inp[1])
    c[inp[1]].add(inp[0])

q = int(input())

for i in range(q):
    s, t = map(int, input().split())
    print(bfs(g, s, t, c))

Python: import sys
input=sys.stdin.readline
n,m=map(int,input().split())
lis=[[]for _ in range(n)]
for _ in range(m):
	s,t=map(int,input().split())
	lis[s].append(t)
	lis[t].append(s)
from collections import deque as dq
queue=dq([])
cnt=0
k=0
color=[-1]*n
while True:
	while k<n:
		if color[k]!=-1:
			k+=1
		else:
			break
	try:
		p=color[k:].index(-1)+k
	except:
		break
	queue.append(p)
	while queue:
		r=queue.popleft()
		color[r]=cnt
		for i in range(len(lis[r])):
			if color[lis[r][i]]==-1:
				queue.append(lis[r][i])
				color[lis[r][i]]=cnt
	cnt+=1
q=int(input())
for _ in range(q):
	s,t=map(int,input().split())
	if color[s]==color[t]:
		print("yes")
	else:
		print("no")