#include<stdio.h>
#include<string.h>
char s[32];
int len;
unsigned long
getNCL(unsigned long new_charLen,unsigned long N){
while(new_charLen>=N) new_charLen>>=1;
return new_charLen;
}
char
getChar(unsigned long N){
printf("%c",s[N]);
}
void
fenzhi(unsigned long new_charLen,unsigned long N){
while(1){
if(N<=len){
N=N<1?len:N;
getChar(N);
return ;
}
N=N-new_charLen-1;
new_charLen=getNCL(new_charLen,N);
}
}
int
main(){
unsigned long N,new_charLen;
scanf("%s%lu",s+1,&N);
s[0]='a'; //填入任意一个字符,以防止s[0]为\0
len=strlen(s);
new_charLen=len;
while(new_charLen<N) new_charLen<<=1; //不能等于
new_charLen>>=1;
fenzhi(new_charLen,N);
return 0;
}