#include <stdio.h>

int a,b,c,T,rez;

int ter(int left,int right,int absolutePrecision)
{
int leftThird,rightThird;
    if (right-left < absolutePrecision) return (left+right)/2;
    leftThird = (left*2+right)/3;
    rightThird = (left+right*2)/3;
    if (leftThird < rightThird)
	return ter(leftThird, right, absolutePrecision);
    else
	return ter(left, rightThird, absolutePrecision);
}

int main()
{
freopen("inundatii.in","rt",stdin);
freopen("inundatii.out","wt",stdout);
scanf("%d", &T);
rez=0;
while (T--)
 {
scanf("%d %d %d", &a,&b,&c);
rez+=ter(a,b,c);
}
printf("%d", rez);
return 0;
}