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 GCD is ', b
END PROGRAM main