为什么有的WA有的RE！！！

#include <iostream>
#include <vector>
using namespace std;
struct Ship {
	int time;
	vector<int> men;
}port[100005];
vector<int> nation;
int main() {
	int n, a = 0;
	cin >> n;
	for (int i = 1; i <= n; i++) {
		cin >> port[i].time;
		int k;
		cin >> k;
		for (int j = 1; j <= k; j++) {
			int input;
			cin >> input;
			port[i].men.push_back(input);
			if (input > nation.size()) {
				for (int l = 1; l <= input - nation.size(); l++) {
					nation.push_back(0);
				}
			}
			nation[input - 1]++;
		}
		while (port[i - 1].time - port[a].time > 86400) {
			a++;
		}
		int sum = 0;
		for (int j = 0; j < nation.size(); j++) {
			if (nation[j] != 0) sum++;
		}
		cout << sum << endl;
	}
	return 0;
}