菜就多练

#include<bits/stdc++.h>
using namespace std;
char ch;
int main()
{
cin >> ch;
if(ch >= 'a' and ch <= 'z'){
cout<< char(ch-'a'+'A') ;
}
else if(ch >= 'A' and ch <= 'Z'){
cout << char(ch - 'A' + 'a');
}
else{
cout << ch;
}
return 0;
}