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]for i in R(5)]
c=d=Y%5
for i in R(4):
	if d<C:
		if d+a[i]*b[i]>C:d+=(C-d+b[i]-1)//b[i]
		else:d+=a[i]*b[i]
print("can't exchange"if Y<C else d if c<C else"no exchange")