#include <stdio.h>

int gcd(int a, int b)
{
  int c;

  while(a != 0) {
    c = a;
    a = b%a;
    b = c;
  }
  return b;
}

int main()
{
  int i, a[5];
  char buf[256];

  printf("1. feladat\n\n  # oldal hosszusaga: ");
  fgets(buf,256,stdin);
  if((a[0] = atoi(buf)) <= 0) printf("  %: nem szamithato ki.\n");
  else {
    printf("  # b oldal hosszusaga: ");
    fgets(buf,256,stdin);
    if((a[1] = atoi(buf)) <= 0) printf("  %: nem szamithato ki.\n");
    else printf("  %: kerulet = %d\n  %: terulet = %d\n",a[0]+a[1],a[0]*a[1]);
  }

  printf("\n2. feladat\n");
  for(i = 0;i < 4;i++) {
    printf("  # %d. szam: ",i+1);
    fgets(buf,256,stdin);
    a[i] = atoi(buf);
    if(i > 0 && a[i] <= a[i-1]) {
      printf("  %: a sorrend nem novekvo.\n");
      break;
    }
  }
  if(i == 4) printf("  %: a sorrend novekvo.\n");

  printf("\n3. feladat\n");
  for(i = 0;i < 4;i++) {
    printf("  # %d. szam: ",i+1);
    fgets(buf,256,stdin);
    if(i > 0) a[0] = gcd(a[0],atoi(buf)); else a[0] = atoi(buf);
    if(a[0] == 1) break;
  }
  printf("  %: lnko = %d\n",a[0]);

  printf("\n4. feladat\n\n  # 1. szam: ");
  fgets(buf,256,stdin);
  a[0] = atoi(buf);
  printf("  # 2. szam: ");
  fgets(buf,256,stdin);
  a[1] = atoi(buf);
  if(a[0] == a[1]) {
    printf("  %: a ket szam ekvivalens.\n");
    return 0;
  }
  printf("%15s\n\n","  %: eredmenyek:");
  if(a[0] < a[1]) a[2] = 0, a[3] = 1; else a[2] = 1, a[3] = 0;
  if(a[a[2]] % 2) {
    a[a[2]]++;
    a[4] = 0;
  } else a[4] = 2;
  for(i = a[a[2]]+a[4];i < a[a[3]];i = i+2) printf("%15d\n",i);
  printf("\n[ENTER] a kilepeshez.\n");
  getchar();
  return 0;
}