#include <bits/stdc++.h>
using namespace std;
bool prime[100000];
int64_t gcd(int64_t a, int64_t b) {
  if (b == 0) return a;
  return gcd(b, a % b);
}
void SieveOfEratosthenes() {
  memset(prime, true, sizeof(prime));
  for (int p = 2; p * p <= 100000; p++) {
    if (prime[p] == true) {
      for (int i = p * p; i <= 100000; i += p) prime[i] = false;
    }
  }
}
long long binpow(long long a, long long b) {
  a %= 1000000007;
  long long res = 1;
  while (b > 0) {
    if (b & 1) res = res * a % 1000000007;
    a = a * a % 1000000007;
    b >>= 1;
  }
  return res % 1000000007;
}
int64_t invmd(int64_t n) { return (binpow(n, 1000000007 - 2)); }
void solve() {
  int n;
  cin >> n;
  vector<vector<int>> dp(n, vector<int>(5, 0));
  for (int i = 0; i < n; i++) {
    for (int k = 0; k < 5; k++) {
      cin >> dp[i][k];
    }
  }
  if (n == 1) {
    cout << 1 << endl;
    return;
  }
  int ma = 0;
  for (int i = 1; i < n; i++) {
    int cnt = 0;
    for (int k = 0; k < 5; k++) {
      if (dp[i][k] < dp[ma][k]) {
        cnt++;
      }
    }
    if (cnt >= 3) {
      ma = i;
    }
  }
  if (ma == 0) {
    cout << 1 << endl;
    return;
  }
  int final = ma;
  for (int i = 0; i < final; i++) {
    int cnt = 0;
    for (int k = 0; k < 5; k++) {
      if (dp[ma][k] > dp[i][k]) {
        cnt++;
      }
    }
    if (cnt >= 3) {
      cout << -1 << endl;
      return;
    }
  }
  cout << ma + 1 << endl;
}
int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  int t;
  cin >> t;
  while (t--) {
    solve();
  }
  return 0;
}
