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#include <algorithm>
#include <cstdio>

const int BASE = 1111111;
const int CLEN = BASE*2;

using namespace std;

int r[504030];
int w[504030];
int t[504030];
int c[2][CLEN];

int main(int argc, char** argv) {
  int n;
  scanf("%d",&n);
  for(int i=0;i<n;i++) {
    scanf("%d%d%d", &(r[i]), &(w[i]), &(t[i]));
  }

  for(int i=0;i<n;i++) {
    c[r[i]-1][BASE+t[i]-w[i]]++;
  }
  int res = 0;
  for(int i=0;i<CLEN;i++) {
    res += min(c[0][i], c[1][i]);
  }
  printf("%d\n", res);
  return 0;
}