题解

#include <bits/stdc++.h>
using namespace std;
char a[10010];
int main()
{
	cin>>a;
	for(int i=0; a[i]; i++)
	{
		if(char(a[i])>=65&&char(a[i])<=90)
			a[i]=char(a[i]+32);
		else if(char(a[i])>=97&&char(a[i])<=122)
			a[i]=char(a[i]-32);
		cout<<a[i];
	}
	return 0;
}