There is a kangaroo at coordinate 0 on an infinite number line that runs from left to right, at time 0. During the period between time i-1 and time i, the kangaroo can either stay at his position, or perform a jump of length exactly i to the left or to the right. That is, if his coordinate at time i-1 is x, he can be at coordinate x-i, x or x+i at time i. The kangaroo's nest is at coordinate X, and he wants to travel to coordinate X as fast as possible. Find the earliest possible time to reach coordinate X.
#!/usr/bin/env python
# -*- coding: utf-8 -*-
#
# FileName: 	C
# CreatedDate:  2020-07-31 13:48:14 +0900
# LastModified: 2020-07-31 14:20:23 +0900
#


import os
import sys
# import numpy as np

from math import sqrt


def main():
    X = abs(int(input()))
    s = (-1+sqrt(1+8*X))/2
    if s.is_integer():
        pass
    else:
        s = int(s) + 1
    print(s)



if __name__ == "__main__":
    main()

#!/usr/bin/env python
# -*- coding: utf-8 -*-
#
# FileName: 	C
# CreatedDate:  2020-07-31 13:48:14 +0900
# LastModified: 2020-07-31 14:24:21 +0900
#


import os
import sys
# import numpy as np

from math import sqrt


def main():
    X = abs(int(input()))
    s = (-1+sqrt(1+8*X))/2
    if s.is_integer():
        s = int(s)
    else:
        s = int(s) + 1
    print(s)



if __name__ == "__main__":
    main()
