import sys input = sys.stdin.readline from heapq import * N=int(input()) A=list(map(int,input().split())) B=list(map(int,input().split())) Ah = [(-a,i+1) for i,a in enumerate(A)] Bh = [(b,i+1) for i,b in enumerate(B)] heapify(Ah) heapify(Bh) i=10000 a,ia = heappop(Ah) b,ib = heappop(Bh) a = -a ans = [] while i>0: if a0: heappush(Ah, (-ab, ia)) if len(Ah)==0:break a,ia = heappop(Ah) a = -a print(len(ans)) for a in ans: print(*a)