package abc;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.BufferedReader;
public class TestSum {
 private static long sum = 0;
 public static void main(String[] args) throws Exception{
  TestSum ts = new TestSum();
  boolean bl = true;
  int n = 0;
  while (bl) {
   System.out.println("计算1！+2!+3!+…+n!，请输入n的值:");
   InputStream is = System.in;
   InputStreamReader isr = new InputStreamReader(is);
   BufferedReader br = new BufferedReader(isr);
   String str = br.readLine();
   boolean b = str.matches("\\d*");
   if (!b) {
    System.out.println("您输入的不是数字！");
    continue;
   }
   n = Integer.parseInt(str);
   if (n >10 || n < 1) {
    System.out.println("请输入小于10并且大于0的数字！");
    continue;   
   }
   bl = false;
  }
  System.out.println(ts.mysum(n));
 }
 public long mysum(int n) {
  int i = n;
  long temp = n;
  for(;i>1;i--){
   temp = temp*(i-1);
  }
  sum = sum + temp;
  if (n>1) {
   mysum(n-1);
  }
  return sum;
 }
}