R=range
C,Y=map(int,input().split())
Y//=100
b=[5,10,20,50,100,11**9]
a=[Y%b[i+1]//b[i]*b[i]for i in R(5)]
c=d=e=Y%5
for n in[0,0]:
	for i in R(4,-1,-1):
		if d<C:
			if d+a[i]>C:d=C+(d+(C-d+b[i]-1)//b[i]*b[i]-C)%5
			else:d+=a[i]
	b[2],b[3],d,e=b[3],b[2],e,d
print("can't exchange"if Y<C else min(d,e)if c<C else"no exchange")