题解

#include<bits/stdc++.h>
using namespace std;

int main()
{
    string s;
    cin >> s;
    for (int i=0;i<s.size();i++)
        s[i]+=((s[i]>='a' && s[i]<='z') ? -32:((s[i]>='A' && s[i]<='Z') ? 32:0));
    cout << s;
    return 0;
}