UVa 10081 - Tight Words

// UVa 10081 - Tight Words

#include <iostream>
#include <stdio.h>
#include <cmath>
using namespace std;

#define datatype double

int main() {
	int k, n;

	while (cin >> k >> n) {
		datatype T[101][10];
		for (int j = 0; j <= k; j++)
			T[1][j] = 1;
		for (int i = 2; i <= n; i++) {
			for (int j = 0; j <= k; j++) {
				T[i][j] = T[i - 1][j];
				if (j < k)
					T[i][j] += T[i - 1][j + 1];
				if (j > 0)
					T[i][j] += T[i - 1][j - 1];
			}
		}
		datatype s = 0;
		for (int j = 0; j <= k; j++)
			s += T[n][j];
		double sol = s * 100.0 / pow(k + 1, n);
		printf("%.5f\n", sol);
	}

	return 0;
}