/*
ZADATAK: proizvod
JEZIK: c++
*/
#include <stdio.h>
#include <algorithm>
FILE *fi,*fo;
using namespace std;
int a[100001],n,m,i;
int f[20],s[20];
int dec[9]={1,10,100,1000,10000,100000,1000000,10000000,100000000};
unsigned long long fege(int *f,int *s,int na,int nb)
{
    unsigned long long sum=0,sum1;
    int i,j;
    for(i=nb-1;i>=0;i--)
     {
       sum1=0;     
       for(j=na-1;j>=0;j--)
         sum1=sum1*10+s[i]*f[j];
        sum=(sum*10+(sum1%dec[m]))%dec[m];
      }
    return sum%dec[m];
}
main()
{
    char x;
    FILE *fi=fopen("proizvod.in","r");
    FILE *fo=fopen("proizvod.out","w");
    unsigned long long res;
    fscanf(fi,"%d%d\n",&n,&m);
    for(i=0;i<n;i++)
      {
            fscanf(fi,"%c",&x);
            a[i]=x-48;
        } 
    sort(a,a+n);
    if(n>2*m+2)
      {
            if(n%2)
             {
                   for(i=0;i<=m;i++)
                     s[i]=a[2*i];
                   for(i=0;i<m;i++)
                     f[i]=a[1+2*i];
                   res=fege(f,s,m,m+1);  
                }
            else
             {
                    for(i=0;i<m;i++)
                     f[i]=a[2*i];
                    for(i=0;i<m;i++)
                      s[i]=a[2*i+1];
                   res=fege(f,s,m,m);
                }
        }
    else
     {
         f[(n/2)-1]=a[n-1];
         s[(n/2)-1+(n%2)]=a[n-2];
         n=n-2;
         if(n%2)
          {
                for(i=0;i<=n/2;i++)
                  s[i]=a[2*i];
                for(i=0;i<n/2;i++)
                  f[i]=a[1+2*i];
                res=fege(f,s,n/2+1,n/2+2);
            }
           else
            {
                for(i=0;i<n/2;i++)
                  f[i]=a[2*i];
                for(i=0;i<n/2;i++)
                  s[i]=a[1+2*i];
                res=fege(f,s,n/2+1,n/2+1);
            }   
        }   
    if(res==0) 
     {
            for(i=1;i<=m;i++)
              fprintf(fo,"0");
              return 0;
        }
    if(res<dec[m-1])
      {
            while(res<dec[m-1])
             {
                    fprintf(fo,"0");
                    m--;
                }
            fprintf(fo,"%llu",res);
        }
    else fprintf(fo,"%llu",res);
    return 0;
}
