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

int main()
{
  char input[100];
  char doubleinput[100];
  int size, address, place1, place2, place3, place4, place5;

  printf("Please enter a noun (\"Done\" = exit): ");
  fgets(input, 100, stdin);
  strcpy(doubleinput, input);
  size = strlen(input);
  place1 = size - 1;
  place5 = size - 2;

  if (input[place1] == 's')
  {
    place2 = place1 + 1;
    place3 = place1 + 2;
    place4 = place1 + 3;
    input[place2] = 'e';
    input[place3] = 's';
    input[place4] = '\0';
  }

  if (input[place5] == 'c' || input[place5] == 's')
  {
    if (input[place1] == 'h')
    {
      place2 = place1 + 1;
      place3 = place1 + 2;
      place4 = place1 + 3;
      input[place2] = 'e';
      input[place3] = 's';
      input[place4] = '\0';
    }
  }
  if (input[place1] == 'y')
  {
    place2 = place1 + 1;
    place3 = place1 + 2;
    place4 = place1 + 3;
    input[place1] = 'i';
    input[place2] = 'e';
    input[place3] = 's';
    input[place4] = '\0';
  }
  else
  {
    place2 = place + 1;
    input[place2] = 's';
  }

  if (input != "Done")
    printf("The plural of %s is %s.\n", doubleinput, input);
  return(0);
}