---

import sys

def main():
    input_data = sys.stdin.read().split()
    if not input_data:
        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])
    
    can1 = (a <= m) and (2 * abs(x) <= d)
    can2 = (b <= m) and (2 * abs(y) <= d)
    
    if not can1 or not can2:
        print(-1)
        return
        
    dist_both = 2 * (max(0, x, y) - min(0, x, y))
    if (a + b <= m) and (dist_both <= d):
        print(1)
    else:
        print(2)

if __name__ == '__main__':
    main()