#include <stdio.h>

int main()
{
	int P, Q, R;
	scanf("%d %d %d", &P, &Q, &R);
	if (P <= Q && P <= R) printf("%.8Lf\n", (long double)(Q + R) / (P + Q + R));
	else if (Q <= P && Q <= R) printf("%.8Lf\n", (long double)(P + R) / (P + Q + R));
	else printf("%.8Lf\n", (long double)(P + Q) / (P + Q + R));
	fflush(stdout);
	return 0;
}