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#pragma GCC optimize ("O3")
#include <bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef pair<int, int> ii;
typedef vector<int> vi;
const int INF = 0x3f3f3f3f;

#define FOR(i,b,e) for(int i = (b); i < (e); i++)
#define TRAV(x,a) for(auto &x: (a))
#define SZ(x) ((int)x.size())
#define PB push_back
#define X first
#define Y second

const int N = 2e6+10;

int cnt[N][2];

void solve(){
    int n, a, b, c, ans = 0;
    cin >> n;
    FOR(i, 0, n){
        cin >> a >> b >> c;
        cnt[b-c+N/2][a-1]++;
    }
    FOR(i, 0, N) ans += min(cnt[i][0], cnt[i][1]);
    cout << ans << '\n';
}

int main(){
    ios::sync_with_stdio(0);
    cin.tie(0);
    // int tt; cin >> tt;
    // FOR(te, 0, tt)
    solve();
    return 0;
}