program free_fall
      write(*,*)'Vx=?'
      read(*,*)vx
      write(*,*)'Vy=?'
      read(*,*)vy
      x=0.0
      y=1.0
      dt=0.0001
      do while (y>=0)
        ax=0.0
        ay=-9.8
        vx=vx+ax*dt
        vy=vy+ay*dt
        x=x+vx*dt
        y=y+vy*dt
      end do
      write(*,*)'Distance=',x,';Hight=',y
      end