import java.util.Scanner;
/**
* @author LLJ
* @time 2020-5-9 15:18:36
* @Description 自定義一個整數數組a,讀入一個整數n,如果n在數組中存在,則輸出n的下標;
* 如果不存在,則輸出-1;
*/
public class Test3 {
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
System.out.println("請輸入一個整數:");
int n = scanner.nextInt();
int a[] = {1,2,5,7,9,11,13,17,19};
int index = isCunzai(n,a);
System.out.println(index);
}
public static int isCunzai(int n,int a[]){
int m = -1;
for (int i = 0; i < a.length; i++) {
if(a[i] == n){
m = i+1;
}
}
return m;
}
}