#include <stdio.h>
#include <string.h>
#include <ctype.h>
#include <stdlib.h> // For exit() function

char *number_1(char tline[]) {
  for (int i = 0, x = strlen(tline); i < x; i++) {
    if (tline[i] == 'a' || tline[i] == 'e' || tline[i] == 'i' || tline[i] == 'o' || tline[i] == 'u' ||
        tline[i] == 'A' || tline[i] == 'E' || tline[i] == 'I' || tline[i] == 'O'  || tline[i] == 'U') {
      memmove(&tline[i], &tline[i+1], strlen(tline)-i);
      i--;
    }
  }
  return tline;
}

char *number_2(char tline[]) {
  int x = strlen(tline);
  for (int i = 0; i < x; i++) {
    if (i > 0 && i < x && tline[i] == tline[i+1]) {
      memmove(&tline[i], &tline[i+1], x-i);
      x--;
    }
  }
  return tline;
}

char *number_3(char tline[]) {
  int alpha_count = 0;
  for (int i = 0, x = strlen(tline); i < x; i++) {
// if we do not count space as character-to-uppercase, uncomment next and add "}"
//      if (isalpha(tline[i])) { // do not count space as character-to-uppercase
//          if (alpha_count++ % 2 == 0 ) {
    if ( i++ % 2 == 0 ) {
      tline [i] = toupper(tline[i]);
    }
  }
  return tline;
}

int main() {
  int number;
  FILE *fip = fopen("input.txt", "r");
  FILE *fop = fopen("output.txt", "w+");
  if (fip == NULL)
  {
    printf("Can't open file!");
    // Program exits if file pointer returns NULL.
    exit(1);
  }

  char line[256]; //magic number of max line size
  printf("Input number of zadazha. Currently available: 1, 2, 3\n");
  scanf("%d", &number);
  while (fgets(line, sizeof(line), fip)) {
    switch (number) {
      case 1: fprintf(fop, "%s", number_1(line)); break;
      case 2: fprintf(fop, "%s", number_2(line)); break;
      case 3: fprintf(fop, "%s", number_3(line)); break;
      default: printf("OH NO! METEORITE RAIN! I SHOULD RUN, BYE!\n");
    }
  }

  fclose(fip);
  fclose(fop);

  return 0;
}