import std;

double calc(int a, int b) {
    double ans = 0;

    const N = 10000;
    double d = 1. * (b - a) / N;
    for (double i = a; i < b; i += d) {
        ans += abs((i - a) * (i - b)) * d;
    }
    return ans;
}

double calc2(int a, int b) {
    return (b - a)^^3 / 6.0;
}

void main() {
    int a, b; scan(a, b);
    writefln("%.10f", calc2(a, b));
}

void scan(T...)(ref T a) {
    string[] ss = readln.split;
    foreach (i, t; T) a[i] = ss[i].to!t;
}
T read(T)() { return readln.chomp.to!T; }
T[] reads(T)() { return readln.split.to!(T[]); }
alias readint = read!int;
alias readints = reads!int;