#include<iostream> using namespace std; int main(){ char c; cin>>c; if（isupper（c)){ c=tolower(c); }else { c=toupper(c); cout<<c<<endl; return 0; }#include<iostream> using namespace std; int main(){ char c; cin>>c; if（isupper（c)){ c=tolower(c); }else { c=toupper(c); cout<<c<<endl; return 0; }#include<iostream> using namespace std; int main(){ char c; cin>>c; if（isupper（c)){ c=tolower(c); }else { c=toupper(c); cout<<c<<endl; return 0; }