#include<bits/stdc++.h>
using namespace std;
using ll = long long;
int t,n,m,k,l,r,op,y;
string x;
ll dfs(ll num,ll ws,ll k){
    if(ws>n){
        if(!k)return num;
        return 0;
    }
    ll ans = dfs(num*10+x[ws]-'0',ws+1,k);
    if(k){
        ans = max(ans,num*dfs(x[ws]-'0',ws+1,k-1));
    }
    return ans;
}
void solve(){
    cin>>n>>k;
    cin>>x;
    x='~'+x;
    cout<<dfs(0,1,k);
}
int main(){
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    cout.tie(nullptr);  
    solve();
    return 0;
}