#include <cstdio>
#define nmax 50010

int sol, n, x[nmax], y[nmax], z[nmax];

void calc()
{
	int i, m;
	m=x[n/2+1]-n/2-1;
	for (i=1; i<=n; i++) 
		if (m+i>x[i]) 
			sol+=m+i-x[i]; else
			sol+=x[i]-m-i;
}

int main()
{
	freopen("inundatii.in","r",stdin);
	freopen("inundatii.out","w",stdout);
	scanf("%d",&n);
	int i;
	for (i=1; i<=n; i++) scanf("%d %d %d",&x[i],&y[i],&z[i]);
	calc();
	for (i=1; i<=n; i++) x[i]=y[i];
	calc();
	for (i=1; i<=n; i++) x[i]=z[i];
	calc();
	printf("%d\n",sol);
}