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#include<bits/stdc++.h>
using namespace std;
using LL = long long;
using D = double;
#define f1 first
#define f2 second
#define randint(a, b) uniform_int_distribution<int>{a, b}(gen)
#ifdef LOC
void OUT() {cout << '\n';}
template<class H, class ... T> void OUT(H h, T ... t)
{
	cout << h << ' ';
	OUT(t...);
}
#define P(...) cout << "[" << #__VA_ARGS__ << "] ", OUT(__VA_ARGS__)
#else
#define P(...)
#define OUT(...)
#endif
//mt19937 gen;

const int offset = 1000100;
int howManyNum[2 * offset][2];

int main(int, char ** /*args*/)
{
	ios_base::sync_with_stdio(0);
	cin.tie(0);
	int n;
	cin >> n;
	int ans = 0;
	for(int i = 0; i < n; ++i)
	{
		int a, b, c;
		cin >> a >> b >> c;
		++howManyNum[offset + b - c][a - 1];
	}
	for(int i = 0; i < 2 * offset; ++i)
	{
		ans += min(howManyNum[i][0], howManyNum[i][1]);
	}
	cout << ans << '\n';
	return 0;
}