#include<stdio.h>
#include<math.h>
double jc(int a)
{
double sum=1;
if (a == 0)
return 1;
for (double s=1; s <= a; s++)
{
sum *= s;
}
return sum;
}
int main()
{
double n, x,i=0;
double sum = 0;
scanf("%lf %lf", &x,&n);
if (n < 0)
{
printf("error");
return -1;
}
for (; i <= n; i++)
{
sum += pow(x, i) / jc(i);
}
printf("%.6f", sum);
return 0;
}