#include<cstdio>
#include<string>
#include<cstring>
using namespace std; 
int main()
{
    freopen("madition.in","r",stdin);
    freopen("madition.out","w",stdout);
    const char LIST[36]={'0','1','2','3','4','5','6','7','8','9','a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z'};
    int i,n,la,lb,a[2000]={0},b[2000]={0};
    char ca[2000]={0},cb[2000]={0};
    scanf("%d\n%s\n%s\n",&n,&ca,&cb);
    la=strlen(ca);
    lb=strlen(cb);
    for(i=0;i<la;i++)
    {
    	if(ca[i]>='0'&&ca[i]<='9')
    	a[la-i-1]=ca[i]-'0';
    	else
    	a[la-i-1]=ca[i]-'a'+10;
    }
    for(i=0;i<lb;i++)
    {
    	if(cb[i]>='0'&&cb[i]<='9')
    	b[lb-i-1]=cb[i]-'0';
    	else
    	b[lb-i-1]=cb[i]-'a'+10;
    }
    if(lb>la)
    la=lb;
    for(i=0;i<la;i++)
    a[i]+=b[i];
    for(i=0;i<la;i++)
    if(a[i]>=n)
    {
    	a[i]-=n;
    	a[i+1]+=1;
    }
    if(a[la]!=0)
    la++;
    for(i=la-1;i>=0;i--)
    printf("%c",LIST[a[i]]);
    printf("\n");
    fclose(stdin);
    fclose(stdout);
    return(0);
}