#include <bits/stdc++.h>
using namespace std;

inline int read(){
    int x=0,f=1;char cc=getchar();
    while(cc<'0' || cc>'9') {if(cc=='-') f=-1;cc=getchar();}
    while(cc>='0' && cc<='9') {x=x*10+cc-'0';cc=getchar();}
    return x*f;
}

int n,a[1010],b[1010],f[1000010],v[1000010];
vector<int> s[2];

int main(){
    for(int tt=read();tt;tt--){
        n=read();
        for(int i=1;i<=n;i++){
            a[i]=read();b[i]=read();
        }
        s[0].clear();
        int x=0;int l=1;int r=1000000;
        while(x<n && max(l,a[x+1])<=min(r,b[x+1])){
            x++;l=max(l,a[x]);r=min(r,b[x]);
        }
        for(int i=1;i<=1000000;i++) v[i]=0;
        f[l]=0;f[r]=0;s[0].push_back(l);if(l<r) s[0].push_back(r);
        int t=0;
        for(int i=x+1;i<=n;i++){
            s[t^1].clear();
            for(int j=0;j<s[t].size();j++){
                if(a[i]<=s[t][j] && s[t][j]<=b[i]){
                    v[s[t][j]]=i;s[t^1].push_back(s[t][j]);
                }
            }
            int d=a[i];
            if(a[i]<=d && d<=b[i]){
                if(v[d]!=i){
                    f[d]=2000000000;v[d]=i;s[t^1].push_back(d);
                }
                for(int j=0;j<s[t].size();j++) f[d]=min(f[d],f[s[t][j]]+(abs(s[t][j]-d)+1)/2);
            }
            d=a[i]+1;
            if(a[i]<=d && d<=b[i]){
                if(v[d]!=i){
                    f[d]=2000000000;v[d]=i;s[t^1].push_back(d);
                }
                for(int j=0;j<s[t].size();j++) f[d]=min(f[d],f[s[t][j]]+(abs(s[t][j]-d)+1)/2);
            }
            d=b[i];
            if(a[i]<=d && d<=b[i]){
                if(v[d]!=i){
                    f[d]=2000000000;v[d]=i;s[t^1].push_back(d);
                }
                for(int j=0;j<s[t].size();j++) f[d]=min(f[d],f[s[t][j]]+(abs(s[t][j]-d)+1)/2);
            }
            d=b[i]-1;
            if(a[i]<=d && d<=b[i]){
                if(v[d]!=i){
                    f[d]=2000000000;v[d]=i;s[t^1].push_back(d);
                }
                for(int j=0;j<s[t].size();j++) f[d]=min(f[d],f[s[t][j]]+(abs(s[t][j]-d)+1)/2);
            }
            t^=1;
        }
        int ans=2000000000;
        for(int i=0;i<s[t].size();i++) ans=min(ans,f[s[t][i]]);
        printf("%d\n",ans);
    }
}