#include <iostream>
#include<string>
#include <iterator>
using namespace std;

int main()
{

string str;
cin>>str;
int count(0);
int len = str.length();
bool flag = true;
char first{str[0]};

if(isupper(first))
{
    for(int i = 1; i<len; i++)
    {
        if(islower(str[i]))
        {
            count++;
        }
    }
}

count = count;


if (count == len - 1){flag = false;}
count = 0;

if(len = 1 && islower(first)){flag = true;}

while(flag)
{
for(auto& i : str)
    {
        if(isupper(i))
        {
            i = tolower(i);
        }
        else if (islower(i))
        {
            i = toupper(i);
        }
    }
break;
}

cout<<str<<endl;

}