简单的dp题

# include <bits/stdc++.h>
using namespace std;
const int N = 5e3 + 10;
int n, w[N], h[N], a[N], dp[N];
int init(int p) {
	if (dp[p]) {
        return dp[p];
    }
    dp[p] = 1;
	for (int i = 0; i <= n; i++) {
		if (w[p] < w[i] && h[p] < h[i] && dp[p] < init(i) + 1) {
			dp[p] = dp[i] + 1;
			a[p] = i;
		}
    }
	return dp[p];
}
int main() {
	scanf("%d", &n);
	for (int i = 0; i <= n; i++) {
		scanf("%d%d", &w[i], &h[i]);
		a[i] = -1;
	}
	init(0);
    printf("%d\n", dp[0] - 1);
	for (int i = a[0]; i != -1; i = a[i]) {
		printf("%d ", i);
    }
    return 0;
}