#include <iostream>
#include <algorithm>

using namespace std;

int main()
{
	int n, max_len = -1, a, b, ans;
	cin >> n;
	if (n == 1) { cin >> n; cout << 1; return 0; }
	cin >> a >> b;
	max_len = (b - a == 1) ? 2 : 1;
	for (int i = 0; i < n - 2; i++) {
		cin >> a;
		(a - b == 1) ? max_len++ : (ans = max(ans, max_len), max_len = 1);
		b = a;
	}
	ans = max(ans, max_len);
	cout << ans;
	return 0;
}

重复提交这份代码，发现测试点乱WA，懵了