n = int(input())
list_ = []
to = list(map(int,input().split()))
min_ = 10 ** 100
min_i = 1
temp = 5 * 10 ** 17
for i in range(0,n - 1):
    a,b = map(int,input().split())
    list_.append([a,b])
    if max(abs(a - temp),abs(b - temp)) < min_:
        min_ = max(abs(a - temp),abs(b - temp))
        min_i = i + 1
print(50)
for i in range(0,50):
    print(1,min_i + 1)