n = input(); d = map(int,raw_input().split()) [x,y] = map(int,raw_input().split()) l = abs(x)+abs(y) if(not(1<=n<=100000)): print("error") for a in d: if(not(1<=a<=1000000000)): print("error") if(not(-1000000000<=x<=1000000000)): print("error") if(not(-1000000000<=y<=1000000000)): print("error") ans = -1 if l == 0: ans = 0 elif l in d: ans = 1 elif l%2==0: if max(d)*2 >= l: ans = 2 else: d.sort() d1 = [x for x in d if x%2==0] d2 = [x for x in d if x%2==1] for t in xrange(2): d1,d2 = d2,d1 if d1 != []: for a in d2: low = 0; high = len(d1)-1 while low < high: mid = (high+low) >> 1; if(a+d1[mid]>=l): high = mid else: low = mid+1 if a+d1[low]