Language: C

#include<stdio.h>
int max(int* matr,int s)
{
  int i,x;
  x=*matr;
  for(i=1;i<s;i++)
  {
    if(*(matr+i)>x) x=*(matr+i);
  }
  return x;
}
int main()
{
  int a,b,c,d,e,f,g,h,i,j,n,max;
  char x,y,z;
  scanf("%d",&n);
  char arr[n];
  int matr[n];
  for(i=0;i<n;i++) 
  {
    arr[i]='a';
    matr[i]=0;
  }
  for(a=1;a<2;a++)
  {
    matr[0]=a;
    printf("%c",96+matr[0]);
    if(n>1)
    {
      for(b=1;b<3;b++)
      {
        matr[1]=b;
        printf("%c",96+matr[1]);
        if(n>2)
        {
          for(c=1;(c<4)&&(c<=(max(matr,2)+1));c++)
          {
            matr[2]=c;
            printf("%c",96+matr[2]);
            if(n>3)
            {
              for(d=1;(d<5)&&(d<=(max(matr,3)+1));d++)
              {
                matr[3]=d;
                printf("%c",96+matr[3]);
                if(n>4)
                {
                  for(e=1;(e<6)&&(e<=(max(matr,4)+1));e++)
                  {
                    matr[4]=e;
                    printf("%c",96+matr[4]);
                    if(n>5)
                    {
                      for(f=1;(f<7)&&(f<=(max(matr,5)+1));f++)
                      {
                        matr[5]=f;
                        printf("%c",96+matr[5]);
                        if(n>6)
                        {
                          for(g=1;(g<8)&&(g<=(max(matr,6)+1));g++)
                          {
                            matr[6]=g;
                            printf("%c",96+matr[6]);
                            if(n>7)
                            {
                              for(h=1;(h<9)&&(h<=(max(matr,7)+1));h++)
                              {
                                matr[7]=h;
                                printf("%c",96+matr[7]);
                                if(n>8)
                                {
                                  for(i=1;(i<10)&&(i<=(max(matr,8)+1));i++)
                                  {
                                    matr[8]=i;
                                    printf("%c",96+matr[8]);
                                    if(n>9)
                                    {
                                      for(j=1;(j<10)&&(j<=(max(matr,9)+1));j++)
                                      {
                                         matr[9]=j;
                                         printf("%c",96+matr[9]);
                                         printf("\n");
                                      }
                                    }
                                    else printf("\n");
                                  }
                                }
                                else printf("\n");
                              }
                            }
                            else printf("\n");
                          }
                        }
                        else printf("\n");
                      }
                    }
                    else printf("\n");
                  }
                }
                else printf("\n");
              }
            }
            else printf("\n");
          }
        }
        else printf("\n");
      }
    }
    else printf("\n");
  }
                                  
  

Compiler output:
main.c: In function 'main':
main.c:36:31: error: called object 'max' is not a function or function pointer
   36 |           for(c=1;(c<4)&&(c<=(max(matr,2)+1));c++)
      |                               ^~~
main.c:14:29: note: declared here
   14 |   int a,b,c,d,e,f,g,h,i,j,n,max;
      |                             ^~~
main.c:42:35: error: called object 'max' is not a function or function pointer
   42 |               for(d=1;(d<5)&&(d<=(max(matr,3)+1));d++)
      |                                   ^~~
main.c:14:29: note: declared here
   14 |   int a,b,c,d,e,f,g,h,i,j,n,max;
      |                             ^~~
main.c:48:39: error: called object 'max' is not a function or function pointer
   48 |                   for(e=1;(e<6)&&(e<=(max(matr,4)+1));e++)
      |                                       ^~~
main.c:14:29: note: declared here
   14 |   int a,b,c,d,e,f,g,h,i,j,n,max;
      |                             ^~~
main.c:54:43: error: called object 'max' is not a function or function pointer
   54 |                       for(f=1;(f<7)&&(f<=(max(matr,5)+1));f++)
      |                                           ^~~
main.c:14:29: note: declared here
   14 |   int a,b,c,d,e,f,g,h,i,j,n,max;
      |                             ^~~
main.c:60:47: error: called object 'max' is not a function or function pointer
   60 |                           for(g=1;(g<8)&&(g<=(max(matr,6)+1));g++)
      |                                               ^~~
main.c:14:29: note: declared here
   14 |   int a,b,c,d,e,f,g,h,i,j,n,max;
      |                             ^~~
main.c:66:51: error: called object 'max' is not a function or function pointer
   66 |                               for(h=1;(h<9)&&(h<=(max(matr,7)+1));h++)
      |                                                   ^~~
main.c:14:29: note: declared here
   14 |   int a,b,c,d,e,f,g,h,i,j,n,max;
      |                             ^~~
main.c:72:56: error: called object 'max' is not a function or function pointer
   72 |                                   for(i=1;(i<10)&&(i<=(max(matr,8)+1));i++)
      |                                                        ^~~
main.c:14:29: note: declared here
   14 |   int a,b,c,d,e,f,g,h,i,j,n,max;
      |                             ^~~
main.c:78:60: error: called object 'max' is not a function or function pointer
   78 |                                       for(j=1;(j<10)&&(j<=(max(matr,9)+1));j++)
      |                                                            ^~~
main.c:14:29: note: declared here
   14 |   int a,b,c,d,e,f,g,h,i,j,n,max;
      |                             ^~~
main.c:110:3: error: expected declaration or statement at end of input
  110 |   }
      |   ^