import java.util.*; public class Main{ public static void main(String [] args){ //Map自带的方法containsKey() /*Scanner sc=new Scanner(System.in); while(sc.hasNext()){ int n=sc.nextInt(); Map<Integer,Integer> map=new HashMap<>(n); for(int i=0;i<n;i++){ int a=sc.nextInt(); int b=sc.nextInt()...