#include <stdio.h>
#include <ctype.h>
int main() {
  char str[100] = {'\0'};
  int i;
  scanf("%s", str);
  for (i = 0; i < 100; i++) {
    if (isupper(str[i]) != 0) {
      str[i] = tolower(str[i]);
    } else if (isupper(str[i]) == 0) {
      str[i] = toupper(str[i]);
    } else {
      break;
    }
  }
  printf("%s\n", str);
}