from collections import Counter N=int(input()) A=list(map(int,input().split())) MINUS=[] ZERO=0 PLUS=[] for a in A: if a<0: MINUS.append(-a) elif a==0: ZERO+=1 else: PLUS.append(a) CM=Counter(MINUS) CP=Counter(PLUS) mans=0 for cp in CP: mans+=min(CP[cp],CM[cp]) mans+=ZERO//2 wans=0 M2=MINUS[:] P2=PLUS[:] M2.sort() P2.sort() ind=0 for i in range(len(M2)): while ind