Minimizing Maximizer

#include <map>
#include <set>
#include <list>
#include <cmath>
#include <queue>
#include <stack>
#include <cstdio>
#include <vector>
#include <string>
#include <cctype>
#include <complex>
#include <cassert>
#include <utility>
#include <cstring>
#include <cstdlib>
#include <iostream>
#include <algorithm>
using namespace std;
typedef pair<int,int> PII;
typedef long long ll;
#define lson l,m,rt<<1
#define rson m+1,r,rt<<1|1
#define All 1,N,1
#define N 50010
#define read freopen("in.txt", "r", stdin)
const ll  INFll = 0x3f3f3f3f3f3f3f3fLL;
const int INF= 0x7ffffff;
const int mod =  1000000007;
struct seg{
    int s,e;
}g[N*10];
int minv[N*4],n,q;
void pushup(int rt){
    minv[rt]=min(minv[rt<<1],minv[rt<<1|1]);
}
void build(int l,int r,int rt){
    if(l==r){
        if(l==1)minv[rt]=0;
        else minv[rt]=INF;
        return;
    }
    int m=(l+r)>>1;
    build(lson);
    build(rson);
    pushup(rt);
}
void update(int p,int l,int r,int rt,int v){
    if(l==r){
        minv[rt]=min(minv[rt],v);
        return;
    }
    int m=(l+r)>>1;
    if(p<=m)update(p,lson,v);
    else update(p,rson,v);
    pushup(rt);
}
int query(int L,int R,int l,int r,int rt){
    if(l>=L&&r<=R)
        return minv[rt];
    int tmp=INF;
    int m=(l+r)>>1;
    if(L<=m)tmp=min(tmp,query(L,R,lson));
    if(R>m)tmp=min(tmp,query(L,R,rson));
    return tmp;
}
int main()
{
    int t;
    scanf("%d",&t);
    while(t--){
        scanf("%d%d",&n,&q);
        for(int i=0;i<q;++i)
        scanf("%d%d",&g[i].s,&g[i].e);
        build(1,n,1);
        for(int i=0;i<q;++i){
            int ans=min(query(g[i].s,g[i].e-1,1,n,1)+1,query(g[i].e,g[i].e,1,n,1));
                update(g[i].e,1,n,1,ans);
        }
        printf("%d\n",query(n,n,1,n,1));
        if(t)printf("\n");
    }
return 0;
}