题解

#include<iostream>
#include<cstring>
using namespace std;
int main(){
    char c[1010];
    cin>>c;
    int n=strlen(c);
    for(int i=0;i<n;i++){
        if(c[i]>='a'&&c[i]<='z'){
            c[i]-=32;
        }else if(c[i]>='A'&&c[i]<='Z'){
            c[i]+=32;
        }
    }
    cout<<c;
    return 0;
}