#include <cstdio>

#include <cstring>

#include <algorithm>

using namespace std;

const int maxn=101;

const int maxm=201;

int n,b;

char a[maxn][maxm];

int len[maxn];

char ans[maxm];

int getnum(char c){

        if(c>='0'&&c<='9')return c-'0';

        return c-'a'+10;

}

char getchar(int t){

        if(t<10)return '0'+t;

        return 'a'+t-10;

}

void add(int ind,int num){

        int tmp=(getnum(ans[ind])+num)%b;

        ans[ind]=getchar(tmp);

}

int main(){

        while(scanf("%d%d",&n,&b)==2){

                int mxlen=0;

                for(int i=0;i<n;i++){

                        scanf("%s",a[i]);

                        len[i]=strlen(a[i]);

                        mxlen=max(mxlen,len[i]);

                }

                for(int i=0;i<mxlen;i++)ans[i]='0';

                ans[mxlen]=0;

                for(int j=1;j<=mxlen;j++){

                        for(int i=0;i<n;i++){

                                if(len[i]>=j){

                                        add(mxlen-j,getnum(a[i][len[i]-j]));

                                }

                        }

                }

                int ind;

                for(ind =0;ans[ind]=='0'&&ind<mxlen-1;ind++){}

                printf("%s\n",ans+ind);

        }

        return 0;

}