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#include <cstdio>
#include <cstring>
#include <cmath>
#include <cassert>
#include <iostream>
#include <algorithm>
#include <iterator>
#include <string>
#include <vector>
#include <queue>
#include <bitset>
#include <utility>
#include <stack>

using namespace std;
typedef long long LL;
typedef pair<int,int> PII;
typedef vector<int> VI;
#define MP make_pair
#define FOR(v,p,k) for(int v=(p);v<=(k);++v)
#define FORD(v,p,k) for(int v=(p);v>=(k);--v)
#define REP(i,n) for(int i=0;i<(n);++i)
#define VAR(v,i) __typeof(i) v=(i)
#define FOREACH(i,c) for(VAR(i,(c).begin());i!=(c).end();++i)
#define PB push_back
#define ST first
#define ND second
#define SIZE(x) (int)x.size()
#define ALL(c) c.begin(),c.end()

#define ODD(x) ((x)%2)
#define EVEN(x) (!(ODD(x)))

const int MX = 2000009;
int dos[2][MX];

int main() {
    int n;
    scanf("%d\n", &n);
    REP(i, n) {
        int r, w, t;
        scanf("%d%d%d", &r, &w, &t);
        r=r%2;
        dos[r][w-t+ MX/2]++;
    }

    int res=0;
    REP(i, MX) {
        res += min(dos[0][i], dos[1][i]);
    }
    
    printf("%d\n", res);
    return 0;
}