#include <map>#include <set>#include <list>#include <cmath>#include <ctime>#include <deque>#include <stack>#include <queue>#include <cctype>#include <cstdio>#include <string>#include <vector>#include <climits>#include <cstdlib>#include <cstring>#include <iostream>#include <algorithm>#define LL long long#define PI 3.1415926535897932626using namespace std;int gcd(int a, int b) {return a % b == 0 ? b : gcd(b, a % b);}double dp[105][15];int N,K;void slove(){    if (K <= 1) {puts("100.00000");return;}    for (int i = 0 ;i < 105; i++) for (int j = 0;j <15; j++) dp[i][j]=0.0;    for (int i = 0 ;i <= K; i++) dp[1][i]=100.0/(double)(K+1);    for (int i = 2; i <= N; i++)    {        dp[i][0] = 1.0/(double)(K+1) * ( dp[i-1][0] + dp[i-1][1]);        for (int j = 1; j <= K ; j++)        {            if (j == K) dp[i][j] = 1.0/(double)(K+1) * (dp[i-1][K] + dp[i-1][K-1]);            else  dp[i][j] = 1.0/(double)(K+1) * (dp[i-1][j-1] + dp[i-1][j] + dp[i-1][j+1]);        }    }    double ans=0.0;    for (int i = 0 ;i <= K; i ++) ans+=dp[N][i];    printf("%.5lf\n",ans);}int main(){    while (scanf("%d%d",&K,&N)!=EOF)    slove();    return 0;}