疑似《AI》代码

#include <bits/stdc++.h>
#define int long long
using namespace std;
void solve()
{
	string s;
	cin >> s;
	int n = s.size();
	if (n == 1)
	{
		cout << s;
		return ;
	}
	for (int i = 0; i < n - 1; i++)cout << 9;
	if (s.substr(0, n - 1) == string(n - 1, '9'))cout << s[n - 1];
}
signed main()
{
	ios::sync_with_stdio(false);
	cin.tie(nullptr);
	int T = 1;
	//cin >> T;
	while (T--)
	{
		solve();
	}
	return 0;
}