#include <bits/stdc++.h>
using namespace std;
int main() {
string s;
int c=0,d=0;
char ch;
cin >> s;
int n = s.size();
if(islower(s[0]))
{
for(int i=1;i<n;i++)
{
if(isupper(s[i]))
{
c++;
}
}
if(c == n-1)
{
s[0] = toupper(s[0]);
for(int i=1;i<n;i++)
{
s[i] = tolower(s[i]);
}
cout << s << endl;
}
else
{
cout << s << endl;
}
}
else if(isupper(s[0])){
for(int i=1;i<n;i++)
{
if(isupper(s[i]))
{
d++;
}
}
if(n-1==d)
{
for(int i=0;i<n;i++)
{
s[i] = tolower(s[i]);
}
cout << s << endl;
}
else
{
cout << s << endl;
}
}
return 0;
}
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