x1 = int(input())
y1 = int(input())
x2 = int(input())
y2 = int(input())

dx = abs(x1 - x2)
dy = abs(y1 - y2)

if ((dx == 1) and (dy == 2) or (dx == 2) and (dy == 1)):
    print("YES")
else:
    print("NO")