USACO 1.3 Barn Repair

/*
ID: aznfy1
PROG: barn1
LANG: C++
*/

#include<stdio.h>
#include<string.h>
#include<algorithm>
#include<iostream>
using namespace std;
int space[200];
int length;
int tmp1,tmp2;
int tmp[400];
int main()
{
    freopen("barn1.in","r",stdin);
    freopen("barn1.out","w",stdout);
    int BoardNum,HomeNum,CowNum;
    while(cin>>BoardNum>>HomeNum>>CowNum)
    {
        int k=0;tmp1=0;
        tmp2=0;
        length=CowNum;
        for(int i=0;i<CowNum;i++)
        {
            cin>>tmp[i];
        }
        sort(tmp,tmp+CowNum);
        for(int i=0;i<CowNum;i++)
        {
            tmp1=tmp[i];
            if(tmp2!=0&&(tmp1-tmp2>1))
            {
                space[k]=tmp1-tmp2-1;
                k++;
            }
            tmp2=tmp1;
        }
        sort(space,space+k);
        for(int i=0;i<k+1-BoardNum;i++)
        {
            length+=space[i];
        }
        cout<<length<<endl;
    }
    return 0;
}