#include<stdio.h>
int main()
{
	int p, q, r;
	scanf("%d %d %d", &p, &q, &r);
	if (p >= r && q >= r)
		printf("%.20lf\n", (double)(p + q) / (p + q + r));
	else if (p >= q && r >= q)
		printf("%.20lf\n", (double)(p + r) / (p + q + r));
	else
		printf("%.20lf\n", (double)(q + r) / (p + q + r));
	return 0;
}