题解2.0

#include <bits/stdc++.h>
using namespace std;
int main() {
//范围：大写65-90 小写97-122;
char l;
cin>>l;
if (65<=(int) (l) && (int) (l)<=90) {
cout<<(char) ((int) (l)+32);
}
else if (97<=(int) (l) && 122>=(int) (l)) {
cout<<(char) ((int) (l)-32);
}
return 0;
}