#include <bits/stdc+

#include <bits/stdc++.h>
using namespace std;
char a[30] = {'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 main(){
int n;
cin >> n;
for(int i = 1;i <= n;i++){
for(int j = 0;j < i;j++){
cout << a[j];
}
cout << endl;
}
return 0;
}