Codeforces_131A

//Codeforces Round 131A
#include <string>
#include <iostream>
using namespace std;
int main()
{
    int len, c=1;
    string s;
    cin >> s;
    len = s.size();
    for(int i=1;i<len;i++)
    {
        if(s[i]>=97&&s[i]<=122)
        {
            c=0;
        }
    }
    if(c==0)
    {
        cout<<s;
    }
    else
    {
        if(s[0]>=97&&s[0]<=122)
        {
            s[0]-=32;
        }
        else
        {
            s[0]+=32;
        }
        for(int i=1;i<s.length();i++)
        {
            s[i]+=32;
        }
        cout<<s;
    }
    return 0;
}