题解

#include<bits/stdc++.h>
using namespace std;
void Aa(string &x){
	for(int i=0;i<x.size();i++){
	if(x[i]>='A'&&x[i]<='Z')x[i]+=32;
	else if(x[i]>='a'&&x[i]<='z')x[i]-=32;
	}
}
int main(){
	string a;
	cin>>a;
	Aa(a);
	cout<<a;
	return 0;
}