1>c:\documents and settings\jennifer\my documents\visual studio 2008\projects\binarytree\binarytree\input.txt(1) : error C2059: syntax error : 'constant'

#include <iostream>
#include <vector>
#include <fstream>
 
using namespace std;
 
int reconstruct(vector<int> const& inorder, vector<int> const& preorder, vector<pair<int, int> >& result, int l, int r, int& index)
{
    if (l > r || index >= preorder.size())
    {
        if (l > r)
            --index;
        return 0;
    }
 
  if (l == r)
        return inorder[l];
 
    int m;
    for (m = l; m <= r; ++m)
        if (inorder[m] == preorder[index])
            break;
 
    int root = preorder[index];
    // searches for root's childs
    int left = reconstruct(inorder, preorder, result, l, m - 1, ++index);
    int right = reconstruct(inorder, preorder, result, m + 1, r, ++index);
    result[root] = make_pair(left, right);
    return root;
}
 
// makes result in level traversal
void makeResult(int root, vector<pair<int, int> > const& tree,
                                 vector<vector<int> >& result, int height)
 
{
  if (root == 0)
        return;
 
    result[height].push_back(root);
    makeResult(tree[root].first, tree, result, height + 1);
    makeResult(tree[root].second, tree, result, height + 1);
}
 
int main(int argc, char* argv[])
{
  ifstream input(argv[1]);
    if (!input)
    {
        cout << "Can't open input file: " << argv[1] << "\n";
        return 1;
    }
 
    int n;
    input >> n;
 
    vector<int> inorder(n), preorder(n);
    for (int i = 0; i < n; ++i)
        input >> inorder[i];
    for (int i = 0; i < n; ++i)
        input >> preorder[i];
 
    int index = 0;
    vector<pair<int, int> > tree(n + 1);
    vector<vector<int> >    result(n);
 
    // recontsruct tree
    int root = reconstruct(inorder, preorder, tree, 0, n - 1, index);
 
    // make level traversal output
  makeResult(root, tree, result, 0);
    // output final result level by level
    for (int i = 0; i < n; ++i)
{
        vector<int>& level = result[i];
        // output all nodes at level i
        for (int j = 0; j < level.size(); ++j)
        {
            cout << level[j] << " " << tree[level[j]].first << " " << tree[level[j]].second << "\n";
        }
    }
    return 0;
}

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