title: Getting negative numbers in C++
body: <p>The question I am trying to solve is Find the thirteen adjacent digits in the 1000-digit number that have the greatest product.. I am trying to figure out when i try to read more than 8. It seems like it isn't running anymore.
  Right now I get the value of 2145402160 but I want to read 13 values. Can someone tell me what I am doing wrong? test.txt file is</p>
  
  <pre><code>73167176531330624919225119674426574742355349194934
  96983520312774506326239578318016984801869478851843
  85861560789112949495459501737958331952853208805511
  12540698747158523863050715693290963295227443043557
  66896648950445244523161731856403098711121722383113
  62229893423380308135336276614282806444486645238749
  30358907296290491560440772390713810515859307960866
  70172427121883998797908792274921901699720888093776
  65727333001053367881220235421809751254540594752243
  52584907711670556013604839586446706324415722155397
  53697817977846174064955149290862569321978468622482
  83972241375657056057490261407972968652414535100474
  82166370484403199890008895243450658541227588666881
  16427171479924442928230863465674813919123162824586
  17866458359124566529476545682848912883142607690042
  24219022671055626321111109370544217506941658960408
  07198403850962455444362981230987879927244284909188
  84580156166097919133875499200524063689912560717606
  05886116467109405077541002256983155200055935729725
  71636269561882670428252483600823257530420752963450
  
  
  
  #include&lt;stdio.h&gt;
  int main()
  {
  int a,b,c,d,e,g,h,j,k,l,m,n,o,p;
  unsigned long long f;
  unsigned long long max = 0;
  FILE *fp;
  fp=fopen("/Users/desktop/test.txt","r");
  fscanf(fp,"%1d",&amp;a);
  fscanf(fp,"%1d",&amp;b);
  fscanf(fp,"%1d",&amp;c);
  fscanf(fp,"%1d",&amp;d);
  fscanf(fp,"%1d",&amp;e);
  fscanf(fp,"%1d",&amp;h);
  fscanf(fp,"%1d",&amp;j);
  fscanf(fp,"%1d",&amp;k);
  fscanf(fp,"%1d",&amp;l);
  fscanf(fp,"%1d",&amp;m);
  fscanf(fp,"%1d",&amp;n);
  fscanf(fp,"%1d",&amp;o);
  
  
  
  
  for(int i=13;i&lt;=1000;i++)
  {
      fscanf(fp,"%1d",&amp;p);
      f=a*b*c*d*e*h*j*k*l*m*n*o*p;
      if(max&lt;f)max=f;
      a=b;
      b=c;
      c=d;
      d=e;
      e=h;
      h=j;
      j=k;
      k=l;
      l=m;
      m=n;
      n=o;
      o=p;
  
  }
  printf("%lld\n",max);
  return 0;
  }
  </code></pre>