Untitled

#include <bits/stdc++.h>
using namespace std;

void MO3TAZOLEQ() {
#ifdef MOATAZOLEQ
    freopen("input.txt", "r", stdin);
    freopen("output.txt", "w", stdout);
#endif
}

#define ll long long

void solve() {
    map<int, int> front, back, same;
    int n;
    cin >> n;
    set<int> s;
    for (int i = 0; i < n; ++i) {
        int x, y;
        cin >> x >> y;
        front[x]++;
        back[y]++;
        s.insert(x);
        s.insert(y);
        if (x == y) {
            same[x]++;
        }
    }
    int ans = 1e9;
    for (auto cand: s) {
        int cnt = front[cand] + back[cand] - same[cand];
        if (cnt * 2 >= n) {
            int need = (n + 1) / 2 - front[cand];
            if (need <= 0) {
                ans = 0;
                break;
            }
            ans = min(ans, need);
        }
    }
    cout << (ans == 1e9 ? -1 : ans);
}

int main() {
    MO3TAZOLEQ();
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);

    int t = 1;
    // cin >> t;
    while (t--) {
        solve();
    }
    return 0;
}