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

double dfs(double x, double y, int k) {
    if (k == 1) return max(x, y) / min(x, y);
    double ans = 999999999.0;
    for (int i = 1; i < k; i++) {
        ans = min(ans, max(dfs(x, y / k * i, i), dfs(x, y / k * (k - i), k - i)));
        ans = min(ans, max(dfs(x / k * i, y, i), dfs(x / k * (k - i), y, k - i)));
    }
    return ans;
}

int main() {
    double x, y; int n;
    scanf("%lf%lf%d", &x, &y, &n);
    printf("%.6lf\n", dfs(x, y, n));
    return 0;
}