n = int(input())
ev = []
a = []
for i in range(n):
    l, r = map(int, input().split())
    a.append((l, r))
    ev.append((l, 1, i))
    ev.append((r, -1, i))
ev.sort()
bal = 0
INF = 10 ** 18
mn = INF
one = -1
two = -1
last = 0
for i in range(2 * n):
    bal += ev[i][1]
    if bal > 0 and ev[i][1] == -1 and i - 1 >= 0 and ev[i - 1][1] == 1:
        if mn > ev[i][0] - ev[i - 1][0] and ev[i][0] - ev[i - 1][0] > 0:
            mn = ev[i][0] - ev[i - 1][0]
            one = ev[i][2]
            two = ev[i - 1][2]
if mn == INF:
    print(0)
elif one != two:
    print(one + 1, two + 1)
else:
    l, r = a[one][0], a[one][1]
    for i in range(n):
        if i != one and a[i][0] <= l and a[i][1] >= r:
            ans = i
            break
    print(ans + 1, one + 1)