from collections import defaultdict
import sys 
sys.setrecursionlimit(1000000)
def push(u,v):
    g[u].add(v)
def dfs(u):
    global go,cnt
    if u not in g:
        return 
    for i in gs[u]:
        while go<i:
            go+=1
            cnt+=1
            dfs(go-1)
        if go==i:
            go+=1
    
            
        
            
for i in range(int(input())):
    n,m=map(int,input().split())
    cnt=0
    g=defaultdict(set)
    st=[0 for i in range(n+10)]
    push(1,n+1)
    for  i in range(m):
        u,v=map(int,input().split())
        u,v=min(u,v),max(u,v)
        push(u,v)
    gs={k:sorted(v) for k,v in g.items() }
    go=2
    dfs(1)
    print(cnt)