import math

def find_xn(x, n):
    if n == 0:
        return x
    
    if x > 0:
        k = math.ceil((math.sqrt(8 * x + 1) - 1) / 2)
        m = k + 1
        # 计算Xm
        sum_k = k * (k + 1) // 2
        Xm = x - sum_k + (k + 1)
    else:
        target = -x
        if target == 0:
            k = 0
        else:
            k = math.ceil((math.sqrt(8 * target + 1) - 1) / 2)
            while k * (k + 1) // 2 <= target:
                k += 1
        m = k
        sum_k = k * (k + 1) // 2
        Xm = x + sum_k
    
    if n < m:
        current = x
        for i in range(1, n + 1):
            if current > 0:
                current -= i
            else:
                current += i
        return current
    else:
        t_steps = n - m
        groups = t_steps // 2
        remainder = t_steps % 2
        Xn = Xm + groups 
        
        if remainder:
            i = m + 2 * groups + 1
            if Xn > 0:
                Xn -= i
            else:
                Xn += i
        return Xn

x, n = map(int, input().split())
print(find_xn(x, n))