---

import sys

def solve():
    input_data = sys.stdin.read().split()
    if len(input_data) < 6:
        return
    
    x = int(input_data[0])
    y = int(input_data[1])
    a = int(input_data[2])
    b = int(input_data[3])
    m = int(input_data[4])
    d = int(input_data[5])

    NoPathForDronRobot = -1

    if a > m or b > m:
        print(NoPathForDronRobot)
        print(NoPathForDronRobot, file=sys.stderr)
        return

    if a + b <= m:
        abs_x = abs(x)
        abs_y = abs(y)
        
        if (x > 0) != (y > 0):
            dist = 2 * (abs_x + abs_y)
        else:
            dist = 2 * max(abs_x, abs_y)
            
        if dist <= d:
            print(1)
            print(1, file=sys.stderr)
            return

    if 2 * abs(x) <= d and 2 * abs(y) <= d:
        print(2)
        print(2, file=sys.stderr)
        return

    print(NoPathForDronRobot)
    print(NoPathForDronRobot, file=sys.stderr)

if __name__ == '__main__':
    solve()