class Solution {
    int answer = 0;
    boolean[] visited;

    public int solution(int k, int[][] dungeons) {
        visited = new boolean[dungeons.length];
        dfs(0, k, dungeons);
        return answer;
    }

    private void dfs(int depth, int k, int[][] dungeons) {
        for (int i = 0; i < dungeons.length; i++) {
            if (!visited[i] && dungeons[i][0] <= k) {
                visited[i] = true;
                dfs(depth+1, k - dungeons[i][1], dungeons);
                visited[i] = false;
            }
        }
        answer = Math.max(depth, answer);
    }
}