﻿namespace topCoder
{
	using System;
	using System.Collections.Generic;

	class FixedDiceGameDiv2
	{
		public double getExpectation(int a, int b)
		{
			double wins, num;
			wins = num = 0;

			for (int B = 1; B <= b; B++)
			{
				for (int A = B + 1; A <= a; A++)
				{
					wins += A;
					num++;
				}
			}

			return wins / num;
		}
	}
}
