Go: package main

import (
	"fmt"
)

var n, m int
var g [][]int
var color []int

func main() {
	fmt.Scan(&n, &m)
	g = make([][]int, n) // SNSの関係を表すグラフ
	for i := 0; i < m; i++ {
		var a, b int
		fmt.Scan(&a, &b)
		g[a] = append(g[a], b) // 無向重みなしグラフ
		g[b] = append(g[b], a)
	}
	color = make([]int, n) // 各ノードにつける色
	for i := 0; i < len(color); i++ {
		color[i] = -1 // 初期化しておく
	}
	type query struct {
		s, t int
	}
	var Q int
	fmt.Scan(&Q)
	qs := make([]query, Q)
	for i := 0; i < Q; i++ {
		fmt.Scan(&qs[i].s, &qs[i].t)
	}
	// fmt.Println("n", n, "m", m, "g", g, "Q", Q, "qs", qs)
	// 全ての頂点からdfsする
	id := 1
	for u := 0; u < n; u++ {
		if color[u] == -1 {
			dfs(u, id)
			id++
		}
	}
	// fmt.Println("color", color)
	for i := 0; i < Q; i++ {
		if color[qs[i].s] == color[qs[i].t] {
			fmt.Println("yes")
		} else {
			fmt.Println("no")
		}
	}
}

func dfs(v, c int) {
	// fmt.Printf("dfs(v %d, c %d) en:\n", v, c)
	color[v] = c
	for _, vv := range g[v] {
		// fmt.Printf("  v %d, g[v] %v, vv %d\n", v, g[v], vv)
		if color[vv] == -1 {
			dfs(vv, c)
		}
	}
}

Python: n,m = map(int,input().split())
B = [[0 for i in range(n)] for j in range(n)]
chk = [0 for i in range(n)]
s = []
i_array = [0 for i in range(n)]
connect = []
cou = 0
node_in = [0 for i in range(n)]

for i in range(m):
    A = list(map(int,input().split()))
    B[A[0]][A[1]] = 1
    B[A[1]][A[0]] = 1

for i in range(n):
    if(chk[i] == 1):
        continue
    chk[i] = 1
    s.append(i)
    connect.append([])
    connect[cou].append(i)
    node_in[i] = cou

    while(len(s) != 0):
        flag = 0
        v = s[len(s)-1]
        for j in range(i_array[v],n):
            if(B[v][j] == 1 and chk[j] == 0):
                chk[j] = 1
                s.append(j)
                connect[cou].append(j)
                node_in[j] = cou
                i_array[v] = j+1
                flag = 1
                break
        if(flag == 0):
            s.pop()

    cou += 1

q = int(input())
for i in range(q):
    start,target = map(int,input().split())
    p = node_in[start]
    flag = 0
    for j in range(len(connect[p])):
        if(connect[p][j] == target):
            print("yes")
            flag = 1
            break
    if(flag == 0):
        print("no")

Python: def tan(G,st,fi):
    global flag
    global flag_list
    for i in range(len(G)):
        if flag_list[i] == 1:
            continue
        if G[st][i] == 1:
            if i == fi:
                flag = 1
            flag_list[i] = 1
            tan(G,i,fi)
    
n,m = list(map(int, input().split()))
G = [[0 for i in range(n)] for j in range(n)]

for i in range(m):
    S = list(map(int, input().split()))
    G[S[0]][S[1]] = 1
    G[S[1]][S[0]] = 1

q = int(input())
ans = []
for i in range(q):
    Q = list(map(int, input().split()))
    flag = 0
    flag_list = [0 for i in range(n)]
    tan(G,Q[0],Q[1])
    if flag==1:
        ans.append("yes")
    else:
        ans.append("no")
        
for i in range(q):
    print(ans[i])

Python: def connected(G,s,t):
    checked = [False]*len(G)
    def main(G,s,t):
        if t in G[s]: return True
        checked[s] = True
        for f in G[s]:
            if checked[f]: continue
            if main(G,f,t): return True
        return False
    return main(G,s,t)


if __name__=='__main__':
    n,m = list(map(int,input().split()))
    G = [[] for _ in range(n)]
    for _ in range(m):
        s,t = list(map(int,input().split()))
        G[s].append(t)
        G[t].append(s)
    q = int(input())
    for _ in range(q):
        s,t = list(map(int,input().split()))
        print('Yes' if connected(G,s,t) else 'No')

Python: import sys


if __name__ == "__main__":
    n, m = map(int, sys.stdin.readline().split())
    setlist = []
    inp = sys.stdin.readlines()
    for i in range(m):
        inp_i = list(map(int, inp[i].split()))
        a = -1
        b = -1
        for j in range(len(setlist)):
            if inp_i[0] in setlist[j]:
                a = j
            if inp_i[1] in setlist[j]:
                b = j
        if a == -1 and b == -1:
            setlist.append(set([inp_i[0], inp_i[1]]))
        elif a == -1:
            setlist[b].add(inp_i[0])
        elif b == -1:
            setlist[a].add(inp_i[1])
        elif a < b:
            c = setlist.pop(a)
            d = setlist.pop(b-1)
            e = c.union(d)
            setlist.append(e)
        elif a > b:
            c = setlist.pop(b)
            d = setlist.pop(a-1)
            e = c.union(d)
            setlist.append(e)
    for i in range(int(inp[m])):
        inp_i = list(map(int, inp[i+m+1].split()))
        if len(setlist) == 0:
            print("no")
        for j in range(len(setlist)):
            if inp_i[0] in setlist[j]:
                if inp_i[1] in setlist[j]:
                    print("yes")
                    break
                else:
                    print("no")
                    break
            if j == len(setlist)-1:
                print("no")

Python: def tan(G,st,fi,flag):
    for i in range(len(G)):
        if G[st][i] == 1:
            print(st,fi,i)
            if i == fi:
                flag == 1
            tan(G,i,fi,flag)
    
n,m = list(map(int, input().split()))
G = [[0 for i in range(n)] for j in range(n)]

for i in range(m):
    S = list(map(int, input().split()))
    G[S[0]][S[1]] = 1

q = int(input())
ans = []
for i in range(q):
    Q = list(map(int, input().split()))
    st = Q[0]
    fi = Q[1]
    flag = 0
    tan(G,Q[0],Q[1],flag)
    if flag==1:
        ans.append("yes")
    else:
        ans.append("no")
        
for i in range(q):
    print(ans[i])

Python: from collections import deque
n,m = [int(i) for i in input().split()]
F = [{} for i in range(n)]
for _ in range(m):
    i,j = [int(i) for i in input().split()]
    F[i][j] = 1
    F[j][i] = 1
q = int(input())
DP = [0 for i in range(n)]
c = 1
d = deque()
for i in range(n):
    if DP[i]:
        continue
    else:
        d.append(i)
    while(len(d)>0):
        tmp = d.pop()
        DP[tmp] = c
        for i in F[tmp]:
            if not DP[i]:
                d.append(i)
    c+=1

for i in range(q):
    s,t = [int(i) for i in input().split()]
    if DP[s] == DP[t]:
        print("yes")
    else:
        print("no")

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


def assignColor():
    for i in range(n):
        if C[i] == -1:
            #BFS(i)
            DFS(i)

def BFS(start):
    global C
    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]

#@profile
def DFS(start):
    S = [start]
    C[start] = start
    while len(S) != 0:
        u = S.pop(0)
        for i in G[u]:
            if C[i] == -1:
                C[i] = start
                S.append(i)

if __name__ == "__main__":
    _input = sys.stdin.readlines()
    n, m = list(map(int, _input[0].split()))
    G = [[] for i in range(n)]
    C = [-1]*n
    
    for i in range(m):
        s, t = list(map(int, _input[i+1].split()))
        G[s].append(t)
        G[t].append(s)
    assignColor()
    q = int(_input[m+1])
    for i in range(q):
        s, t = list(map(int, _input[m+i+2].split()))
        if C[s] == C[t]:
            print("yes")
        else:
            print("no")