#include 
     
      #include 
      
       #include 
       
        #define N 501using namespace std;int n;double p;double pa[N][N];double pow[N];void Init(){    memset(pa,0,sizeof(pa));    pow[0]=1;    for(int i=1;i
        
         =0)                pa[i][j]=pa[i-1][j]-pa[i-j-2][j]*(1-p)*pow[j+1];        }    }    double ans = 0;    for(int i=1;i<=n;i++)    {        ans += (pa[n][i]-pa[n][i-1])*i;    }    printf("%.6lf\n",ans);}int main(){    while(scanf("%d %lf",&n,&p)!=EOF && n)    {        Init();        Do();    }    return 0;}