$\Huge题目$

按照标称写的数据（手打，不是用的文件读写）为什么 $\color{red}WA$ 了？？

#include<bits/stdc++.h>
#include<regex>
using namespace std;
string m_t_h(const string& m) 
{
    string r = m;
    r = regex_replace(r, regex("^# (.*)$"), "<h1>$1</h1>");
    r = regex_replace(r, regex("^## (.*)$"), "<h2>$1</h2>");
    r = regex_replace(r, regex("^### (.*)$"), "<h3>$1</h3>");
    r = regex_replace(r, regex("__(.*?)__"), "<strong>$1</strong>");
    r = regex_replace(r, regex("_(.*?)_"), "<em>$1</em>");
    r = regex_replace(r, regex("~~(.*?)~~"), "<del>$1</del>");
    
    return r;
}
int main() 
{
    int n;
    cin>>n;
    cin.ignore();
    for(int i=1;i<=n;i++) 
	{
        string m;
        getline(cin,m);
        cout << m_t_h(m) << "\n";
    }
    return 0;
}