#include <bits/stdc++.h>

using namespace std;
const int INF = 0x3f3f3f3f;

// 2760 r1
// 4800 0.57
// r3
/**
 测试用例：
 2700 5000

 答案:
 1358.00
 *
 */
int l1 = 2760, l2 = 4800;
double r1 = 0.52, r2 = 0.57, r3 = 0.82;
int main() {
    int a, b;
    cin >> a >> b;
    if (a <= l1 && b <= l1)
        printf("%.2lf", (b - a) * r1);
    else if (a <= l1 && b <= l2 && b > l1)
        printf("%.2lf", (l1 - a) * r1 + (b - l1) * r2);
    else if (a <= l1 && b > l2)
        printf("%.2lf", (l1 - a) * r1 + (l2 - l1) * r2 + (b - l2) * r3);
    else if (a > l1 && b > l1 && a <= l2 && b <= l2)
        printf("%.2lf", (b - a) * r2);
    else if (a > l1 && a <= l2 && b > l2)
        printf("%.2lf", (l2 - a) * r2 + (b - l2) * r3);
    else if (a > l2 && b > l2)
        printf("%.2lf", (b - a) * r3);
    return 0;
}