#include <iostream>
#include <fstream>
#define NMAX 50000

using namespace std;

ifstream f("inundatii.in");
ofstream g("inundatii.out");

int n;
long long sol;
struct punct
{   long long x, y, z;
}v[NMAX+10];

int main()
{
    f >> n;
    for(int i=1; i<=n; i++)
        {   f >> v[i].x >> v[i].y >> v[i].z;
            if(i > 1)
                {   if(v[i].x <= v[i-1].x) sol = sol + v[i-1].x - v[i].x + 1, v[i].x = v[i].x + (v[i-1].x - v[i].x) / 2 + 1;
                    if(v[i].y <= v[i-1].y) sol = sol + v[i-1].y - v[i].y + 1, v[i].y = v[i].y + (v[i-1].y - v[i].y) / 2 + 1;
                    if(v[i].z <= v[i-1].z) sol = sol + v[i-1].z - v[i].z + 1, v[i].z = v[i].z + (v[i-1].z - v[i].z) / 2 + 1;
                }
        }
    g << sol << '\n';
    return 0;
}