考察一行內的元素輸入和獲取:

import java.io.BufferedReader;
import java.io.InputStreamReader;

public class Main {

    public static void main(String[] args) throws Exception{
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        String[] str = br.readLine().split(" ");
        
 
int index = 1;
        for(String s: str) {
            if(!s.equals("250")) {
                index++;
            } else {
                System.out.print(index);
                break;
            }
        }

    }

}