heap usage

Greetings
I was wondering if someone could could help me out with a problem concerning heaps. I have a vector of a struct that contains a string and a int i.e.
typedef struct wordusage
{
string word;
int num;
};
I want to create a heap based on the integer so I can easily find the largest "num"s in the vector. make_heap of course won't operate on my struct, so how can I heap the int without losing its corresponding string?

Why won't make_heap() work on your struct ?

Code:

---

#include <algorithm>
#include <string>
#include <vector>
#include <iostream>

using namespace std;

struct wordusage
{
    string word;
    int num;
};

struct sort_function
{
    inline bool operator () (const wordusage & lhs , const wordusage & rhs)
    {
        return lhs.num < rhs.num;
    }
};

int main()
{
    vector<wordusage> v;

    wordusage w1;
    w1.word ="hello";
    w1.num = 2;
    v.push_back(w1);

    wordusage w2;
    w2.word ="world";
    w2.num = 5;
    v.push_back(w2);

    wordusage w3;
    w3.word ="and";
    w3.num = 10;
    v.push_back(w3);

    wordusage w4;
    w4.word ="zebra";
    w4.num = 1;
    v.push_back(w4);

    wordusage w5;
    w5.word ="red";
    w5.num = 3;
    v.push_back(w5);

    make_heap(v.begin(),v.end(),sort_function());

    vector<wordusage>::iterator i;
    for (i=v.begin(); i!=v.end(); ++i)
    {
        cout << (*i).num << " " << (*i).word << endl;
    }

    return 0;
}

---

Silly me, I forgot to include a sort method. Thanks for the input!