题解

#include<bits/stdc++.h>
using namespace std;
int main(){
string s;
getline(cin,s);
int y=s.size();
for(int i=0;i<=y-1;i++){
if(s[i]>='a' and s[i]<='z'){
s[i]-=32;
}else if(s[i]>='A' and s[i]<='Z'){
s[i]+=32;
}
cout<<s[i];
}
return 0;
}