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#include<bits/stdc++.h>

using namespace std;
const int MAX_W=1000000;
const int ARR_SIZE = MAX_W*2;
int tracks[2][ARR_SIZE] = {0};

int main(){
    int n; cin >> n;
    int r, w, t;
    while(n--){
        cin >> r >> w >> t;
        ++tracks[r-1][w-t-1+MAX_W];
    }
    long long count = 0;
    for(int i=0; i<ARR_SIZE; i++){
        count += min(tracks[0][i], tracks[1][i]);
    }
    cout << count;
}