#include <stdio.h>
#include <ctype.h>

int main(void){
    char s;
    while(1){
        s = getchar();
        if(isupper(s)){
            s = tolower(s);
            printf("%c", s);
        }else if(islower(s)){
            s = toupper(s);
            printf("%c", s);
        }else{
            printf("\n");
            break;
        }
    }
    return 0;
}