program main
    implicit none 
 integer :: a, b, c
   print*, "Enter Two positive integers"
 read*,  a, b
 if (a < b) then   
      c = a     
      a = b
      b = c
end if
   do                     
   c = MOD(a, b)      
      IF (c == 0) EXIT     
      a = b                 
      b = c         
 end do              
   print*, "The HCF is ", b
end program main