#include <iostream> #include <vector> #include <algorithm> #include <climits>

using namespace std;

int main() { int n; cin >> n;

vector<pair<int, int>> dominoes(n);
int top_sum = 0, bottom_sum = 0;

for (int i = 0; i < n; ++i) {
    cin >> dominoes[i].first >> dominoes[i].second;
    top_sum += dominoes[i].first;
    bottom_sum += dominoes[i].second;
}

int min_diff = abs(top_sum - bottom_sum);
int min_flips = 0;

vector<vector<int>> dp(n + 1, vector<int>(2 * 6 * n + 1, INT_MAX));
dp[0][6 * n] = 0;  // 初始状态，差值为0，翻转次数为0

for (int i = 0; i < n; ++i) {
    int a = dominoes[i].first;
    int b = dominoes[i].second;
    int diff = a - b;
  
    for (int j = 0; j <= 2 * 6 * n; ++j) {
        if (dp[i][j] != INT_MAX) {
            // 不翻转当前骨牌
            int new_j = j + diff;
            if (new_j >= 0 && new_j <= 2 * 6 * n) {
                if (dp[i + 1][new_j] > dp[i][j]) {
                    dp[i + 1][new_j] = dp[i][j];
                }
            }
          
            // 翻转当前骨牌
            new_j = j - diff;
            if (new_j >= 0 && new_j <= 2 * 6 * n) {
                if (dp[i + 1][new_j] > dp[i][j] + 1) {
                    dp[i + 1][new_j] = dp[i][j] + 1;
                }
            }
        }
    }
}

for (int j = 0; j <= 2 * 6 * n; ++j) {
    if (dp[n][j] != INT_MAX) {
        int current_diff = abs(j - 6 * n);
        if (current_diff < min_diff) {
            min_diff = current_diff;
            min_flips = dp[n][j];
        } else if (current_diff == min_diff && dp[n][j] < min_flips) {
            min_flips = dp[n][j];
        }
    }
}

cout << min_flips << endl;
return 0;

}