#include <stdio.h>
#include <stdlib.h>
#include <string.h>

char* solution(int n, int k) {
    // Start with all 'a's (minimum possible)
    char* result = (char*)malloc(n + 1);
    for (int i = 0; i < n; i++) {
        result[i] = 'a';
    }
    result[n] = '\0';
    
    // Calculate remaining value needed
    int remaining = k - n;
    
    // Fill from right to left with largest possible letters
    for (int i = n - 1; i >= 0; i--) {
        if (remaining == 0) break;
        
        // Maximum we can add to current position (z - a = 25)
        int addValue = remaining < 25 ? remaining : 25;
        
        // Update the character
        result[i] = 'a' + addValue;
        
        // Reduce remaining value
        remaining -= addValue;
    }
    
    return result;
}

int main() {
    int n, k;
    scanf("%d %d", &n, &k);
    char* result = solution(n, k);
    printf("%s\n", result);
    free(result);
    return 0;
}