题解

#include <iostream>
#include <string>
using namespace std;

int main()
{
string s;
string s1,s2;
cin>>s;
for(int i=0;i<s.size();i++)
{
if(i%2==0)
{
s1=s1+s[i];
}
else
{
s2=s2+s[i];
}
}
cout<<s2<<s1;
return 0;
}