COMMON /VAR/ x_min,x_max,x_step,y_min,y_max,y_step
      COMMON /TABLE/ n,m
      COMMON /PI/ pi
      COMMON /eps/ eps,epsx,epsy
      pi=3.1415926
      eps=0.0001
      CALL INPUT
      CALL COLUMNS
      CALL OUTPUT
      END

      SUBROUTINE INPUT
      COMMON /VAR/ x_min,x_max,x_step,y_min,y_max,y_step
      COMMON /eps/ eps,epsx,epsy
      OPEN (1,FILE='input.txt')
      READ (1,*) x_min,x_max,x_step,y_min,y_max,y_step
      CLOSE(1)
      CALL EPS_X_Y
      IF (x_min.GT.x_max.OR.y_min.GT.y_max)THEN
      PRINT *,'The minimum is greater than the maximum'
      PAUSE
      STOP
      END IF

      IF (x_step.LT.0.OR.y_step.LT.0)THEN
      PRINT *,'Negative step'
      PAUSE
      STOP
      END IF

      IF (ABS(x_step).LE.epsx.AND.(x_max-x_min).GT.epsx) THEN
      PRINT *,'Incorrect data'
      PAUSE
      STOP
      END IF

      IF (ABS(y_step).LE.epsy.AND.(y_max-y_min).GT.epsy) THEN
      PRINT *,'Incorrect data'
      PAUSE
      STOP
      END IF

      IF(x_step.GT.epsx) THEN
      IF (ABS(DEGREE(x_max)-DEGREE(x_step)).GE.4.OR.
      >     ABS(DEGREE(x_min)-DEGREE(x_step)).GE.4)THEN
      PRINT *,'Invisible step by x'
      PAUSE
      STOP
      END IF
      END IF

      IF(y_step.GT.epsy) THEN
      IF (ABS(DEGREE(y_max)-DEGREE(y_step)).GE.4.OR.
      >     ABS(DEGREE(y_min)-DEGREE(y_step)).GE.4)THEN
      PRINT *,'Invisible step by y'
      PAUSE
      STOP
      END IF
      END IF
      END

      SUBROUTINE COLUMNS
      COMMON /TABLE/ n,m
      COMMON /VAR/ x_min,x_max,x_step,y_min,y_max,y_step
      COMMON /eps/ eps,epsx,epsy

      IF (ABS(x_step).LE.epsx.OR.(x_max-x_min).LE.epsx)THEN
      n=1
      ELSE
      IF (ABS(MOD((x_max-x_min),x_step)).LE.eps)THEN
      n=(x_max-x_min+x_step/2)/x_step+1
      ELSE
      n=(x_max-x_min)/x_step+2
      END IF
      END IF

      IF (ABS(y_step).LE.epsy.OR.(y_max-y_min).LE.epsy)THEN
      m=1
      ELSE
      IF (ABS(MOD((y_max-y_min),y_step)).LE.eps)THEN
      m=(y_max-y_min+y_step/2)/y_step+1
      ELSE
      m=(y_max-y_min)/y_step+2
      END IF
      END IF
      END

      SUBROUTINE OUTPUT
      COMMON /VAR/ x_min,x_max,x_step,y_min,y_max,y_step
      COMMON /TABLE/ n,m
      COMMON /PI/ pi
      COMMON /eps/ eps,epsx,epsy
      x_current=x_min
      y_current=y_min

      OPEN(2, file='output.txt')
      WRITE(2,20)'x\y    '   
      DO i=0,m-2
      IF ((ABS(y_current+y_step)).GE.(ABS(1E-04*(y_current)))) THEN
      y_current=y_min+y_step*i
      WRITE (2,10) y_current
      ELSE 
      y_current=0
      WRITE (2,10) y_current
      END IF
      END DO

      WRITE(2,10) y_max
      WRITE(2,50)
      write(2,20) '-----------'
      DO i=1,m
      write(2,40) '-----------'
      END DO
      WRITE(2,50)

      DO i=0,n-1 
      IF((x_min + x_step * i).GT.x_max)THEN
      x_current = x_max
      ELSE
          IF(ABS(x_min + x_step * i).LE.epsx)THEN
          x_current = 0
          ELSE
          x_current = x_min + x_step * i
      END IF
      END IF
      WRITE (2,30) x_current
      y_current=y_min
      DO j=1,m
        IF(ABS(COS((x_current+y_current)*pi/180)).LE.eps) THEN
        WRITE(2,40)'inf    '
        ELSE
          IF(ABS(SIN((x_current+y_current)*pi/180)).LE.eps) THEN
          func=0E4
          WRITE(2,10) func
          ELSE
          func=TAN((x_current+y_current)*pi/180)
          WRITE (2,10) func
          END IF
        END IF
        IF(ABS(y_min + y_step * j).LE.epsy)THEN
        y_current = 0
        ELSE 
        y_current=y_min+y_step*j
        END IF
        IF((y_min + y_step * j).GT.y_max)THEN
        y_current = y_max
        END IF
        END DO
      WRITE(2,60)
      END DO

      10    FORMAT(E11.4,'|'\)
      20    FORMAT(A11,'||'\) 
      30    FORMAT(E11.4,'||'\)
      40    FORMAT(A11,'|'\) 
      50    FORMAT(A1)
      60    FORMAT(A1,\)
      END

      SUBROUTINE EPS_X_Y
      COMMON /VAR/ x_min,x_max,x_step,y_min,y_max,y_step
      COMMON /eps/ eps,epsx,epsy

      IF(x_step.NE.0)THEN
      IF(ABS(x_min).LE.ABS(x_step).AND.x_min.NE.0) THEN
      J1=DEGREE(x_min)
      ELSE
          IF(ABS(x_max).GE.ABS(x_step).AND.x_step.NE.0) THEN
          J1=DEGREE(x_step)
          ELSE
          J1=DEGREE(x_max)
          END IF
      END IF
      ELSE
      IF(ABS(x_max).GE.ABS(x_min).AND.x_min.NE.0) THEN
          J1=DEGREE(x_min)
          ELSE
          J1=DEGREE(x_max)
      END IF
      END IF

      IF (J1.GE.0)THEN
      epsx=(10**J1)*1E-4
      ELSE
      epsx=1
      DO i=2, ABS(J1)
      epsx=epsx/10
      END DO
      epsx=epsx*1E-4
      END IF

      IF(y_step.NE.0)THEN
      IF(ABS(y_min).LE.ABS(y_step).AND.y_min.NE.0) THEN
      J2=DEGREE(y_min)
      ELSE
          IF(ABS(y_max).GE.ABS(y_step).AND.y_step.NE.0) THEN
          J2=DEGREE(y_step)
          ELSE
          J2=DEGREE(y_max)
          END IF
      END IF
      ELSE
      IF(ABS(y_max).GE.ABS(y_min).AND.y_min.NE.0) THEN
          J2=DEGREE(y_min)
          ELSE
          J2=DEGREE(y_max)
      END IF
      END IF 

      IF (J2.GE.0)THEN
      epsy=(10**J2)*1E-4
      ELSE
      epsy=1
      DO i=2, ABS(J2)
      epsy=epsy/10
      END DO
      epsy=epsy*1E-4
      END IF
      END

      REAL FUNCTION DEGREE(a)
      IF (a.EQ.0) THEN 
      DEGREE=0 
      ELSE
      DEGREE=AINT(log10(ABS(a)))
      END IF
      RETURN
      END