#include <cstdio>

#include <algorithm>

int xx, yy, n;

double slove(double x, double y, int left) {

	if (left == 1) {

		return x > y? x / y: y / x;

	}

	double rt = 1.0e100, tx = x / left, ty = y / left;

	for (int i = 1; i <= (left >> 1); ++i) {

		rt = std::min(rt, std::max(slove(tx * i, y, i), slove(tx * (left - i), y, left - i)));

		rt = std::min(rt, std::max(slove(x, ty * i, i), slove(x, ty * (left - i), left - i)));

	}

	return rt;

}

int main(void) {

	scanf("%d%d%d", &xx, &yy, &n);

	printf("%.6f\n", slove((double)xx, (double)yy, n));

	return 0;

}