#include <bits/stdc++.h>
using namespace std;
ifstream f ("heavymetal.in");
ofstream g ("heavymetal.out");
int n,m,i,j,nr,in,sum;
struct spec
{
    int x,y,timp;
} v[100001],ax;

int main()
{
    f>>n;
    for(i=1; i<=n; i++)
    {
        f>>v[i].x>>v[i].y;
        v[i].timp=(v[i].y-v[i].x);
    }
    for(i=1; i<n; i++)
        for(j=i+1; j<=n; j++)
            if(v[i].y<v[j].y)
                ax=v[i],v[i]=v[j],v[j]=ax;
    for(i=1; i<=n; i++) cout<<v[i].x<<" "<<v[i].y<<endl;
    in=v[1].x;
    sum+=v[1].timp;
    cout<<endl;
    cout<<v[1].x<<" "<<v[1].y<<endl;
    for(i=2; i<=n; i++)
    {
        if(v[i].y<=in)
        {
            //if(v[i].x==v[i+1].x && v
            sum+=v[i].timp;
            in=v[i].x;
            cout<<v[i].x<<" "<<v[i].y<<endl;
        }
    }
    g<<sum;

    return 0;
}