int main(){
int l, n, i, k = 0, t;
int a[10];
cin>>l>>n;
--n;// 第n个就是下标为n-1
while (n){
t = n % 26;
if (t) a[k++] = t;
else a[k++] = 0;
n /= 26;
}
for (; k < l; ++k)a[k] = 0;
for (i = k - 1; i >= 0; --i){
printf("%c", 25 - a[i] + 'a');
}
printf("
");
return 0;
}
int main(){
int L,N;
int a[10];
scanf("%d %d",&L,&N);
N--;
int flag=0;
while(N>0){
a[++flag]=N%26;
N=N/26;
}
for(int i=1;i<=L-flag;i++){
printf("z");
}
for(int i=flag;i>=1;i--){
printf("%c",'z'-a[i]);
}
return 0;
}