求教，是不能用字符串做吗 WA 返回以下信息

Wrong Answer. wrong answer On line 1 column 1, read (ASCII 13), expected 5.

#include <bits/stdc++.h>
using namespace std;
int main()
{
	string aa;
	getline(cin,aa);
	for(register int i=aa.length()-1;i>=0;i--)
	{
		cout<<aa[i];
	}
}

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