只能拿90分

爱信不信

#include <cstring>
using namespace std;
int main(){
 	char a[505];
	cin.getline(a,505);
	int len=strlen(a);
	for(int i=0;i<len;i++){
	    if('a'<=a[i]&&a[i]<='z'){
		    a[i]-=32;
		    cout<<a[i];
		}
		else if('A'<=a[i]&&a[i]<='z'){
			    a[i]+=32;
			    cout<<a[i];
		}
		else cout<<a[i];
	}
	return 0;
}