10212

#include <bits/stdc++.h>
using namespace std;
#define PB push_back
#define ZERO (1e-10)
#define INF (1<<29)
#define CL(A,I) (memset(A,I,sizeof(A)))
#define DEB printf("DEB!\n");
#define D(X) cout<<"  "<<#X": "<<X<<endl;
#define EQ(A,B) (A+ZERO>B&&A-ZERO<B)
typedef long long ll;
typedef long double ld;
typedef pair<ll,ll> pll;
typedef vector<int> vi;
typedef pair<int,int> ii;
typedef vector<ii> vii;
#define IN(n) int n;scanf("%d",&n);
#define FOR(i, m, n) for (int i(m); i < n; i++)
#define REP(i, n) FOR(i, 0, n)
#define F(n) REP(i, n)
#define FF(n) REP(j, n)
#define FT(m, n) FOR(k, m, n)
#define aa first
#define bb second
void ga(int N,int *A){F(N)scanf("%d",A+i);}
int sl(int N,int K){
    int h,t(0),f(0),L(1);
    FT(K,N+1){
        h=k;
        while(!(h&1))++t,h>>=1;
        while(!(h%5))++f,h/=5;
        L*=h,L%=10;
    }
    if(f>t){
        f-=t;
        F(f)L*=5,L%=10;
    }else{
        t-=f;
        F(t)L<<=1,L%=10;
    }
    return L;
}
int main(void){
    int N,M;
    while(~scanf("%d%d",&N,&M))
        printf("%d\n",sl(N,N-M+1));
    return 0;
}