注意开浮点数
import java.util.Scanner;
public class Main {
static Scanner sc=new Scanner(System.in);
public static void main(String[] args) {
double t=0;
int cnt=0;
double distance=1000;
while(distance>=1){
//相撞时间
t=distance/60.0;
distance-=t*20;
cnt++;
}
System.out.println(cnt/2);
}
}