use strict;
use warnings;
use utf8;

my $n = <>;
my %p;
my %q;
for (my $i = 0; $i < $n; $i++) {
    my ($a, $b, $t) = split / /, <>;
    $a==0 ? $p{$b-$t}++ : $q{$b-$t}++; 
}

my $ans = 0;
for my $k (keys %p) {
    $ans += $p{$k} * $q{$k};
}
print $ans, "\n";