#include <algorithm>
#include <iomanip>
#include <iostream>
#include <limits>
#include <vector>

// Intentionally incorrect: Alice always uses the uniform distribution.
int main() {
    std::ios::sync_with_stdio(false);
    std::cin.tie(nullptr);

    int tests;
    std::cin >> tests;
    std::cout << std::fixed << std::setprecision(15);
    while (tests--) {
        int n, m;
        std::cin >> n >> m;
        std::vector<double> column_sum(m, 0.0);
        for (int i = 0; i < n; ++i) {
            for (int j = 0; j < m; ++j) {
                double a;
                std::cin >> a;
                column_sum[j] += a;
            }
        }
        double answer = std::numeric_limits<double>::infinity();
        for (double sum : column_sum) answer = std::min(answer, sum / n);
        std::cout << answer << '\n';
    }
}