mencari program berhenti bila di input angka 99 pada bahasa c

//Program Ini Dibuat Oleh Muhammad Andi Mubaroq//
//NIM: A11.2014.08438
//Tanggal: 14/10/2014
#include <stdlib.h>
#include <string.h>
#include <stdio.h>
main()
{
    int  a,b, nilai;
    int k,l,n,i;

    printf("\t ================================================================ \n");
    printf("\t |                                                              |\n");
    printf("\t |            Nama        :   Muhammad Andi Mubaroq             |\n");
    printf("\t |            NIM         :   A11.2014.08438                    |\n");
    printf("\t |            Kelompok    :   A11.4109                          |\n");
    printf("\t |                                                              |\n");
    printf("\t ================================================================ \n");

    printf("\n\t           PROGRAM BERHENTI BILA DI INPUTKAN ANGKA -99 \n");
    printf("\t ================================================================ \n");
    //==============================================================================//
    for (a=1; nilai!=-99; a++)
    {
        printf("\t Masukkan Data Nilai\t: ");
        scanf("%d", &nilai);
    }
        printf("\n\t Keluar Karena Break\n\n");

    //==============================================================================//

        //deklarasi string x
      char x[]="\t ========= Terima Kasih Selamat Belajar!!! =========== \n";
      n=strlen(x);

      //perulangan sebanyak panjang string
      for(i=0; i<n; i++)
        {
                  /*perulangan untuk menimbulkan jeda waktu
                  antar penampilan karakter*/
                  for(k=0; k<99999;k++)
                  {
                        for(l=0; l<500; l++)
                        {
                        }
                  }
                  //mencetak string x per karakter
                  printf("%c",x[i]);
        }
        return 0;

}