# precondition: input  x > 0
# postcondition (goal):  y >= x

x = readInt()
#PREMISES FOR ATTACHED PROOF, IF ANY: 
# True
#PREMISES FOR NEXT LINE: 
assert x > 0
#PREMISES FOR NEXT LINE: 
# (x > 0)
"""{ 1.OK  x > 0    premise  }"""
#PREMISES FOR NEXT LINE: 
# (x > 0)

y = 2 * x
#PREMISES FOR ATTACHED PROOF, IF ANY: 
# (y == (2 * x))
# (x > 0)
"""{ 1.OK  x > 0         premise
     2.OK  y == 2 * x    premise
     3.OK  y > x         algebra 1 2
}"""
#PREMISES FOR NEXT LINE: 
# (y > x)

x = x + 1
#PREMISES FOR ATTACHED PROOF, IF ANY: 
# (x == (x_old + 1))
# (y > x_old)
"""{ 1.OK  y > x_old        premise
     2.OK  x == x_old + 1   premise
     3.OK  x_old == x - 1   algebra 2
     4.OK  y > x - 1        subst 3 1
     5.OK  y >= x           algebra 4
}"""
#PREMISES FOR NEXT LINE: 
# (y >= x)