#include <stdio.h>
#include "genlib.h"
#include "simpio.h"

int factorial(int n);

main()
{
  int i, n;
  double sum;

  printf("How many terms to compute? ");
  n = GetInteger();

  sum = 0.0;
  for (i = 0; i < n; i++) {
    sum += 1.0 / factorial(i);
  }
  printf("e is approximately %.10f\n", sum);
}

int factorial(int k)
{
  int i, product;

  product = 1;
  for (i = 1; i <= k; i++) {
    product *= i;
  }
  return product;
}