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

int main() {
    int c = 0;
    while(1) {
        c = getchar();
    }
    if (c == islower(c)) {
        c = toupper(c);
    }
    else if (c == isupper(c)) {
        c = tolower(c);
    }
    return 0;
}