a, b = [int(i) for i in input().split()]
e, f, h = 25, -1, False
for i in range(int(input())):
    c, d = [int(j) for j in input().split()]
    if i == 0 and c > a:
        h = True
        break
    if c < e:
        e = c
    if d > f:
        f = d
if h:
    print("NO")
elif e <= a and f >= b:
    print("YES")
else:
    print("NO")