Solution.java

import java.util.*;
import java.util.stream.*;

public class Solution {
    public static long solve(List<List<Integer>> events) {
        Map<String, Long> costs = new HashMap<>();
        long totalCost = 0;
        
        for (List<Integer> event : events) {
            int type = event.get(0);
            if (type == 1) {
                int from = event.get(1);
                int to = event.get(2);
                int fee = event.get(3);
                String key = from + "-" + to;
                costs.put(key, costs.getOrDefault(key, 0L) + fee);
            } else if (type == 2) {
                int from = event.get(1);
                int to = event.get(2);
                String key = from + "-" + to;
                totalCost += costs.getOrDefault(key, 0L);
            }
        }
        return totalCost;
    }
    
    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        int q = scan.nextInt();
        List<List<Integer>> a = new ArrayList<>();
        for (int i = 0; i < q; i++) {
            List<Integer> row = new ArrayList<>();
            int type = scan.nextInt();
            row.add(type);
            if (type == 1) {
                row.add(scan.nextInt());
                row.add(scan.nextInt());
                row.add(scan.nextInt());
            } else if (type == 2) {
                row.add(scan.nextInt());
                row.add(scan.nextInt());
            }
            a.add(row);
        }
        long result = solve(a);
        System.out.println(result);
        scan.close();
    }
}