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

/* written on new year's eve 2020
 * good night and good riddance */

char newchar(char c, int i) {
  switch(i) {
    case 0:
      if(isupper(c)) return c + 32;
      if(c == 33) return -2;
      else return c;
    case 1:
      if(islower(c)) return c - 32;
      if(c == 33) return -2;
      else return c;
    default: return -1;
  }
}
int advi(int i) {
  switch(i) {
    case 0: return 1;
    case 1: return 0;
    default: return -1;
  }
}
int main(void) {
  char c;
  int i = 0;
  while((c = getchar()) != EOF) {
    putchar(newchar(c, i));
    i = advi(i);
  }
}