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#include<bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>

#define rep(i,poczatek,koniec)  for(__typeof(koniec) i = poczatek; i<=koniec; ++i)
#define repr(i,poczatek,koniec) for(__typeof(koniec) i = poczatek; i>=koniec; --i)
#define pb push_back
#define pob pop_back
#define eb emplace_back
#define pf push_front
#define pof pop_front
#define st first
#define nd second
#define bend(X) X.begin(),X.end()
#define sz(X) (int(X.size()))
#define graph vector<node>
#define print cout<<
#ifdef LOCAL
#define nl endl
#define dbg(x) cout << #x << " = " << x << ' ';
#define say(x) cout << x
#else
#define nl '\n'
#define dbg(x)
#define say(x)
#endif

using namespace std;
using namespace __gnu_pbds;

using ll 	= long long;
using ull 	= unsigned long long;
using ld 	= long double;
using pii 	= pair<int,int>;
using pll 	= pair<ll,ll>;
using pli	= pair<ll,int>;
using vb 	= vector<bool>;
using vc 	= vector<char>;
using vi 	= vector<int>;
using vl 	= vector<ll>;
using vpi 	= vector<pii>;
using vpl	= vector<pll>;
using vvi	= vector<vi>;
using vvl 	= vector<vl>;
using vvb	= vector<vb>;

template <typename T> using ordered_set = tree<T, null_type, less<T>, rb_tree_tag,tree_order_statistics_node_update>;

template<typename T1, typename T2> istream& operator>>(istream& is, pair<T1,T2>& x){
	is >> x.st >> x.nd;
	return is;
}
template<typename T1, typename T2> ostream& operator<<(ostream& os, pair<T1,T2>& x){
	os << '(' << x.st << ',' << x.nd << ')';
	return os;
}
template<typename T> istream& operator>>(istream& is, vector<T>& x){
	for(T& i : x)is >> i;
	return is;
}
template<typename T> ostream& operator<<(ostream& os, vector<T> x){
	for(T& i : x)os << i << ' ';
	return os;
}
template<typename T1, typename T2> pair<T1,T2> operator+(const pair<T1,T2>& A, const pair<T1,T2>& B){
	return {A.st + B.st, A.nd + B.nd}; 
}
template<typename T1, typename T2> pair<T1,T2> operator-(const pair<T1,T2>& A, const pair<T1,T2>& B){
	return {A.st - B.st, A.nd - B.nd}; 
}
template<typename T1, typename T2> pair<T1,T2> operator-(const pair<T1,T2>& A){
	return {-A.st, -A.nd};
}
template<typename T1, typename T2> void mine(T1& A, const T2& B){if(B < A) A = B;}
template<typename T1, typename T2> void maxe(T1& A, const T2& B){if(B > A) A = B;}

const int INF 	= (int)2e9;
const ll INFll 	= (ll)9e18;
const int MOD 	= (int)1e9+7;

int R(int pocz, int kon){
	return (rand()%(kon-pocz+1) + pocz);
}

ll RR(ll pocz, ll kon){
	return ((ll((rand()) << 30) + rand())/(kon-pocz+1) + pocz);
}

void fastDataTransfer(){
	ios_base::sync_with_stdio(0);
	cin.tie(0);
	cout.tie(0);
}

const int N = 1e6+5;

int n, m, a, b, c, d, q, k;
int T[N*2+5][3];

void read(){
	cin >> n;
	rep(i,1,n){
		cin>>a>>b>>c;
		T[b-c+N][a]++;
	}
	int ans = 0;
	rep(i,0,int(N)*2)
		ans+=min(T[i][1],T[i][2]);
	print ans << nl;
}

void solve(){
	
}

int main(){
	fastDataTransfer();
	int testCases = 1;
//	cin >> testCases;
	rep(testNumber, 1, testCases){
		read();
		solve();
	}
}