#include <stdio.h>
#include <stdlib.h>
int main()
{int i,j,m;
printf("please input n:");
scanf("%d\n",&m);
for (i = m; i >= 0; i--)
{
for (j = -m; j <= m; j++)
{
if (abs(i) + abs(j) < m && (j - i) % 2)
printf("%c", (j - i + m - 1) / 2 + 'a');
else
printf(" ");
}
printf("\n");
}
return 0;
}