include<iostream>

using namespace std;

int main()
{
int p,v,k;
int a, b,c,d;
cin >>p>>v;
k=v-p;
a=(k/10);
b=(k-(k/10)10)/5; c=(k%5)/2; d=k-(a10+b5+c2);
cout<<a+b+c+d;
return 0;
}