Finding LCM and GCD (HCF)

Menu driven program to obtain LCM or HCF of a given number of inputs.

#include<iostream.h>
#include<conio.h>
#include<stdlib.h>

void lcm()
{
    int i,j,n,lcm,lo,hi=1,arg['z'];     //lo= loop operator
      cout<<"\nEnter No. Terms of Which LCM is Desired....(2 or more):\n";
      cin>>n;
      cout<<"\nEnter the Nos. of Which LCM is to be Found:\n";
      for(i=0;i<n;++i)
        {
            cin>>arg[i];//take input of all numbers
         }
      for(i=0;i<n;++i)
        {
            hi=hi*arg[i]; //find the product of all the inputs (highest possibility for LCM)
         }
      for(i=1,lo=arg[0];i<n;++i)
        {
        if(lo<arg[i])
        {
                lo=arg[i];//to find the lowest possibility for LCM
               }
         }
      for(lo;lo<=hi;++lo)
         {
          for(j=0;j<n;++j)
          {
      if(lo%arg[j]!=0) //to check divisibility of each number starting form lowest possibility to highest to confirm LCM
        {
        break;  //even a single no. is indivisible process stops and restarts
          }
               }
    if(j==n)   // complete cyle of j loop means the no. is divisible by all hence LCM.
        {
        cout<<"The LCM is : "<<lo;
            getch();
            exit(0);
        }
      }
 }

/*----------------------------------------------------*/

void gcd()
{
      int i,j,n,gcd,hi,arg['z'];     //lo= loop operator
      cout<<"\nEnter No. Terms of Which LCM is Desired....(2 or more):\n";
      cin>>n;
      cout<<"\nEnter the Nos. of Which LCM is to be Found:\n";
      for(i=0;i<n;++i)
        {
            cin>>arg[i];//take input of all numbers
         }
      for(i=1,hi=arg[0];i<n;++i)
        {
        if(hi>arg[i])
        {
           hi=arg[i];//to find the highest possibility for GCD
           }
         }
      for(i=hi;i>=hi;i--)
        {
           for(j=0;j<n;j++)
              {
                if(arg[j]%i!=0)
                  {
                      break;
                   }
              }
           if(j==n)
              {
                cout<<"The HCF is : "<<i;
                getch();
                exit(0);
              }
         }
   }

/*----------------------------------------------------*/

void main()
{
    int opt;
      menu:
      clrscr();
      cout<<"Choose from one of the option:-\n1.Find LCM <Press 1>\n2.Find GCD <Press 2>\n";
      cin>>opt;
      switch(opt)
      {
          case 1: lcm();break;
            case 2: gcd();break;
          default: goto menu;
         }
      getch();

   }