#include <iostream>
#include <memory.h>
#include <map>
#include <string>
#include <functional>
#include <vector>
using namespace std;
typedef long long ll;
const ll mod=100000000000;
int main() {
ios::sync_with_stdio(false);
ll n, k;
cin >> n >> k;
ll res =0;
ll tmp = 0;
ll a;
for (ll i = 0; i <= n; i++)
{
tmp = tmp * i;
if (i == 0)
tmp = 1;
a = 1;
for (int j = 0; j < k; j++)
a = (tmp*a) % mod;
res = res + a;
}
while (1)
{
if (res == 0)
return 0;
if (res % 10) {
cout << res % 10 << endl;
return 0;
}
else
res =res/ 10;
}
}