不解释了

#include<bits/stdc++.h>
using namespace std;
int main()
{
int n,cnt=0,sum=-1;
string s;
cin >> n >> s;
int left=0,right=n-1;
while(left<right)
{
int l=left,r=right;
while(s[l]!=s[r]&&l<=r)
{
r--;
}
if(lr)
{
if(n%20)
{
cout<<"Impossible";
return 0;
}
else
{
if(sum>=0)
{
cout<<"Impossible";
return 0;
}
else
{
sum=l;
right++;
}
}

    }
    else if(r != right)
    {
        for(int i=r;i<right;i++)
        {
            swap(s[i],s[i+1]);
            cnt++;
        }
    }
    left++;
    right--;
}
if(sum >= 0)
{
    cnt += n/2 - sum;
}
cout<<cnt;
return 0;

}