human
Solve in Python:
There is a city with $N$ numbered $0 - N-1$ shops. A market is a place where we can reach from one shop to another using some road. There are $M$ roads in this city connecting each connecting any two shops. 
Find the number of markets in the city.
NOTE:  A market having only one shop is also a valid market.

-----Input:-----
- First line will contain $T$, number of testcases. Then the testcases follow. 
- First line of Each Test Case is $N, M$, denoting the number of shops and the number of roads respectively.
- Next M lines consist of two integers $A$ and $B$ denoting that there exists a road between Shop A and Shop B

-----Output:-----
For each testcase, output the number of markets.

-----Constraints-----
- $1 \leq T \leq 100$
- $1 \leq N,M \leq 10^3$
- $0 \leq A,B < N$

-----Sample Input:-----
1
5 3
0 1
2 3
3 4

-----Sample Output:-----
2
 What is a Python program to find the number of markets in the city?
assistant
#Here is Python program to find the number of markets in the city.

class DSU(object):
    def __init__(self, n):
        self.parents = [i for i in range(n)]
    
    def find(self,x):
        if self.parents[x] != x:
            self.parents[x] = self.find(self.parents[x])
        return self.parents[x]
    
    def union(self, x, y):
        rootA, rootB = self.find(x), self.find(y)
        if rootA != rootB:
            self.parents[rootA] = rootB

def solve():
	n,m=map(int,input().split())
	dsu=DSU(n)
	for i in range(m):
		x,y=map(int,input().split())
		dsu.union(x,y)
	cnt=0
	for i,x in enumerate(dsu.parents):
		cnt+=(i==x)
	print(cnt)

t=int(input())
while t:
	solve()
	t-=1