// Arup Guha
// 1/8/2024
// Solution to COP 3503 RP5 Problem: Tight words
// https://open.kattis.com/problems/tight

import java.util.*;

public class tight {

	public static void main(String[] args) {
	
		Scanner stdin = new Scanner(System.in);
		
		// Keep going as long as there is input.
		while (stdin.hasNext()) {
			
			// Get input.
			int numD = stdin.nextInt();
			int n = stdin.nextInt();
			
			// Set up dp. dp[i][j] is probability of a tight word with length i, ending in j.
			double[][] dp = new double[n+1][numD+1];
			for (int i=0; i<=numD; i++)
				dp[1][i] = 1.0/(numD+1);
			
			// Num digits.
			for (int i=2; i<=n; i++) {
			
				// Ending digit.
				for (int j=0; j<=numD; j++) {
				
					// Can always append the same digit.
					dp[i][j] = dp[i-1][j]/(numD+1);
					
					// Add digit j-1 to end to keep it tight.
					if (j>0) dp[i][j] += dp[i-1][j-1]/(numD+1);
					
					// Add digit j+1 to end to keep it tight.
					if (j<numD) dp[i][j] += dp[i-1][j+1]/(numD+1);
				}
			}
			
			// Add up all cases w/diff ending digit.
			double res = 0;
			for (int i=0; i<=numD; i++)
				res += dp[n][i];
			System.out.println(100*res);
		}
	}
}