#include <stdio.h>
2 #include <math.h>
3
4 #define PI 3.14159265358979323846264338327950L
5
6 int main(void) {
7 int a, b, h, m;
8 scanf("%d%d%d%d", &a, &b, &h, &m);
9
10 long double rad = PI * 2 * (
11 (long double)h / 12.0 + ((long double)m / 60.0) / 12.0 - (long
double)m / 60.0);
12
13 long double rsq = (long double)(a * a + b * b) - (long double)(2 * a *
b) * cosl(rad);
14
15 printf("%20.20Lf\n", sqrtl(rsq));
16
17 return 0;
18 }