a, b = map(int, input().split())
if b - a > 10:
print(0)
else:
d = 1
for i in range(a+1, b+1):
d = d * i % 10
print(d)#include <bits/stdc++.h>
#include <iostream>
using namespace std;
typedef long long ll;
#define go() ios::sync_with_stdio(0); cin.tie(0); cout.tie(0)
const int M=1e9+7;
int add(int a,int b)
{
return (a%M+b%M)%M;
}
ll multi(ll a,ll b,ll m)
{
return (a%m*b%m)%m;
}
ll factorial(ll n,ll x)
{
int ans=1;
return ( x == 0 ) ? 1 : multi(n , factorial(n - 1 , x - 1) , 10);
}
int main()
{
go();
ll a,b; cin>>a>>b;
ll x=b-a;
if(x>10) cout<<0<<endl;
else cout<<(factorial(b,x)%10);
}
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