#include<bits/stdc++.h>
using namespace std;
#define endl '\n'
typedef long long ll;
#define int long long
int n,m;
void solve()
{ cin>>n>>m;
m=pow(26,n)-m;
string s;
while(m){
int ti=m%26;
s+=char('a'+ti);
m=m/26;
}
for(int i=s.size()+1;i<=n;i++) s+=char('a');
reverse(s.begin(),s.end());
cout<<s;
}
signed main()
{
ios::sync_with_stdio(false);
cin.tie(0),cout.tie(0);
solve();
return 0;
}