x = readInt() 
#PREMISES FOR ATTACHED PROOF, IF ANY: 
# True
#PREMISES FOR NEXT LINE: 

if x < 0:
    #PREMISES FOR THEN-ARM: 
    # (x < 0)
    """{ 1.OK x < 0    premise  }"""
    #PREMISES FOR NEXT LINE: 
    # (x < 0)
    x = 0 - x
    #PREMISES FOR ATTACHED PROOF, IF ANY: 
    # (x == (0 - x_old))
    # (x_old < 0)
    """{ 1.OK x == 0 - x_old     premise
       2.OK x_old < 0            premise
       3.OK x > 0                algebra 1 2
    }"""
    #PREMISES FOR NEXT LINE: 
    # (x > 0)
else:
    #PREMISES FOR ELSE-ARM: 
    # not (x < 0)
    """{ 1.OK not(x < 0)   premise
       2.OK x >= 0         algebra 1
    }"""
    #PREMISES FOR NEXT LINE: 
    # (x >= 0)
    pass
    #PREMISES FOR NEXT LINE: 
    # (x >= 0)
    """{ 1.OK x >= 0       premise }"""
    #PREMISES FOR NEXT LINE: 
    # (x >= 0)
#PREMISES FOR NEXT LINE: 
# ((x > 0) or (x >= 0))

# prove here that  x >= 0 :

"""{ 1.OK (x > 0)  or  (x >= 0)    premise
     2.OK x >= 0                   ore 1
}"""
#PREMISES FOR NEXT LINE: 
# (x >= 0)