简单

#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;
}