题解

#include<iostream>
#include<cstring>
#include<string>
using namespace std;
int main(){
char a,b;
cin>>a;
if(a>='a' && a<='z'){
b=a-32;
cout<<b;

}
else if(a>='A' && a<='Z'){
    b=a+32;
        cout<<b;
}else{
    cout<<a;
}
return 0;

}