#include<stdio.h>

void razlomak ( int b1, int i1, int b2, int i2 );
int nzd ( int x, int y );
int nzs ( int x, int y );
void sabiranje ( int b1, int i1, int b2, int i2, int *x, int *y );
void oduzimanje ( int b1, int i1, int b2, int i2, int *x, int *y );
void mnozenje ( int b1, int i1, int b2, int i2, int *x, int *y );
void deljenje ( int b1, int i1, int b2, int i2, int *x, int *y );
void uprosti ( int b, int i, int *x, int *y );


main()
{
   int b1,b2,i1,i2;
   printf("\n Unesite razlomke :");
   scanf("%d %d %d %d",&b1,&i1,&b2,&i2);
   if(b1*b2*i1*i2)
      razlomak(b1,i1,b2,i2);
   else
   {
       printf("\n POGRESAN UNOS!\n\a");
       getchar();
   }
return 0;
}

void razlomak ( int b1, int i1, int b2, int i2 )
{
   char c;
   int x,y;
   printf("\n sabiranje  --> + \n");
   printf(" oduzimanje --> - \n");
   printf(" mnozenje   --> * \n");
   printf(" deljenje   --> / \n");
   printf(" uprosti    --> ? \n");
   printf(" izlaz      --> Esc\n\n");
   getchar();
   for (;;)
   {

       printf(" operacija --------> ");
       c = getchar();
       switch (c)
       {
          case '+' : sabiranje(b1,i1,b2,i2,&x,&y);
                     uprosti(x,y,&x,&y);
		     if (x)
                        printf("\n\n\n %d/%d + %d/%d = %d/%d\n\n",b1,i1,b2,i2,x,y);
		     else printf("\n\n\n %d/%d + %d/%d = 0\n\n",b1,i1,b2,i2);
                     getchar();
		     break;

          case '-' : oduzimanje(b1,i1,b2,i2,&x,&y);
                     uprosti(x,y,&x,&y);
		     if (x)
                        printf("\n\n\n %d/%d - %d/%d = %d/%d\n\n",b1,i1,b2,i2,x,y);
		     else
                        printf("\n\n\n %d/%d - %d/%d = 0\n\n",b1,i1,b2,i2);
                        getchar();
		     break;
          case '*' : mnozenje(b1,i1,b2,i2,&x,&y);
                     uprosti(x,y,&x,&y);
		     printf("\n\n\n %d/%d * %d/%d = %d/%d\n\n",b1,i1,b2,i2,x,y);
                     getchar();
		     break;
          case '/' : deljenje(b1,i1,b2,i2,&x,&y);
                     uprosti(x,y,&x,&y);
		     printf("\n\n\n %d/%d / %d/%d = %d/%d\n\n",b1,i1,b2,i2,x,y);
                     getchar();
		     break;
          case '?' : uprosti(b1,i1,&x,&y);
		     printf("\n\n\n %d/%d = %d/%d ,  ",b1,i1,x,y);
		     uprosti(b2,i2,&x,&y);
		     printf("%d/%d = %d/%d\n\n",b2,i2,x,y);
                     getchar();
		     break;
           case '!': printf("\n\n\n izlaz\n");
                     return;
          default  :  printf("\n\n\n greska pri unosu\n");
                      break;
     }
   }
 }

int nzd ( int x, int y )
{
  if (x%y)
	  return (nzd(y,x%y));
   else
	   return y;
 }

int nzs ( int x, int y )
{
return (x*y/nzd(x,y));
}

void sabiranje ( int b1, int i1, int b2, int i2, int *x, int *y )
{
   if (i1 == i2)
   {
       *y = i1;
       *x = b1+b2;
   }
   else
   {
       *y = nzs(i1,i2);
       *x = nzs(i1,i2)/i1*b1+nzs(i1,i2)/i2*b2;
   }
}

void oduzimanje ( int b1, int i1, int b2, int i2, int *x, int *y )
{
   if (i1 == i2)
   {
       *y = i1;
       *x = b1-b2;
   }
   else
   {
       *y = nzs(i1,i2);
       *x = nzs(i1,i2)/i1*b1-nzs(i1,i2)/i2*b2;
   }
}

void mnozenje ( int b1, int i1, int b2, int i2, int *x, int *y )
{
   *x = b1 * b2;
   *y = i1 * i2;
}

void deljenje ( int b1, int i1, int b2, int i2, int *x, int *y )
{
   *x = b1 * i2;
   *y = i1 * b2;
}

void uprosti ( int b, int i, int *x, int *y )
{
   int n;
   while ((n = nzd(b,i))!=1)
   {
      b/=n;
      i/=n;
   }

   *x = b; *y = i;
}