n,*t=map(int,open(a:=0).read().split())
d=90
c=[0]*d
p=[[]for i in' '*d]
for i in range(n):x,y=t[i*2:-~i*2];z=y%9*10+(x+5*(y%18>8))%10;c[z]+=1;p[z]+=i+1,
t=0
for i in range(d):
 if t<c[i]:t=c[i];a=i
print(t)
print(*p[a])