#include <bits/stdc++.h>
 int ucln(int x,int y)
    {int t;
     while(x!=y)
          {if (x<y) y=y-x;
           else x=x-y;}
     t=x;
     return t;}
 main()
 {int a,b,c,d,tcong,mcong,ttru,mtru,tchia,mchia,tnhan,mnhan;
  printf("Nhap tu so cua phan so thu nhat a=");
  scanf("%d",&a);
  printf("Nhap tu so cua phan so thu hai c=");
  scanf("%d",&c);
  do{printf("\n Nhap mau so khac 0 cua phan so thu nhat b=");
        scanf("%d",&b);}
  while(b==0);
  do{printf("\n Nhap mau so khac 0 cua phan so thu hai d=");
        scanf("%d",&d);}
  while(d==0);
  if(a*d+b*c==0) printf ("\n Tong hai phan so %d/%d + %d/%d = 0",a,b,c,d);
  else
     {tcong=(a*d+b*c)/ucln(a*d+b*c,b*d);mcong=b*d/ucln(a*d+b*c,b*d);
      printf ("\n Tong hai phan so %d/%d + %d/%d = %d/%d",a,b,c,d,tcong,mcong);}
  if(a*d-b*c==0) printf ("\n Hieu hai phan so %d/%d - %d/%d = 0",a,b,c,d);
  else
     {ttru=(a*d-b*c)/ucln(a*d-b*c,b*d);mcong=b*d/ucln(a*d-b*c,b*d);
      printf ("\n Hieu hai phan so %d/%d - %d/%d = %d/%d",a,b,c,d,ttru,mtru);
      printf ("\n Hieu hai phan so %d/%d - %d/%d = %d/%d",c,d,a,b,-ttru,mtru);}
  if(a*c==0) printf ("\n Tich hai phan so %d/%d * %d/%d = 0",a,b,c,d);
  else
     {tnhan=a*c/ucln(a*c,b*d);mnhan=b*d/ucln(a*c,b*d);
      printf ("\n Tich hai phan so %d/%d * %d/%d = %d/%d",a,b,c,d,tnhan,mnhan);}
  if(a==0&&c==0) printf ("\n Hai phan so deu bang 0, khong the thuc hien phep chia");
  else
     {if(a==0) printf ("\n Thuong 2 phan so %d/%d : %d/%d = 0",a,b,c,d);
      if(c==0) printf ("\n Thuong 2 phan so %d/%d : %d/%d = 0",c,d,a,b);
      if(a*c!=0) 
        {tchia=a*d/ucln(a*d,b*c);mchia=b*c/ucln(a*d,b*c);
         printf ("\n Thuong 2 phan so %d/%d : %d/%d = %d/%d",a,b,c,d,tchia,mchia);
         printf ("\n Thuong 2 phan so %d/%d : %d/%d = %d/%d",c,d,a,b,mchia,tchia);}
     }
  getch();
 }