N = int(input())
A = list(map(int, input().split()))

xs = [(a, i) for i, a in enumerate(A)]
xs.sort(key=lambda x: x[0])

a = xs[:N]
b = xs[N:]

s = 0
pairs = []
for x, y in zip(a, b):
    s += y[0] - x[0]
    pairs.append((x[1], y[1]))

print(s)
for x, y in pairs:
    print(x+1, y+1)