新手题解

#include<bits/stdc++.h>
using namespace std;
int main(){
    char a;
    cin>>a;
    if(a >= 'A' && a <= 'Z'){
        cout<<char(a+32);
    }else if(a >= 'a' && a <= 'z'){
        cout<<char(a-32);
    }else{
        cout<<a;
    }
    
    return 0;
}