#include <iostream>
#include <string>
using namespace std;
int main()
{int i, k;
string s;

cin >>s;
k=0;
for (i=0; i<s.length();i++)
	{if (isupper(s[i])== true)
	k++;}
if (k==s.length())
	{for (i=0; i<s.length();i++)
	s[i]=tolower(s[i]);}
else if((k==s.length()-1)&&(islower(s[0])== 2))
	{s[0]=toupper(s[0]);
for (i=1; i<s.length();i++)
	s[i]=tolower(s[i]);}

	cout<<s;
system ("pause");
return 0;
}