SGU 127 Telephone directory

#include<iostream>
#include<vector>
#include<algorithm>
#include<cstdio>
#include<queue>
#include<stack>
#include<string>
#include<map>
#include<set>
#include<cmath>
#include<cassert>
#include<cstring>
#include<iomanip>
using namespace std;

#ifdef _WIN32
#define i64 __int64
#define out64 "%I64d\n"
#define in64 "%I64d"
#else
#define i64 long long
#define out64 "%lld\n"
#define in64 "%lld"
#endif

#define FOR(i,a,b)      for( int i = (a) ; i <= (b) ; i ++)
#define FF(i,a)         for( int i = 0 ; i < (a) ; i ++)
#define FFD(i,a)        for( int i = (a)-1 ; i >= 0 ; i --)
#define S64(a)          scanf(in64,&a)
#define SS(a)           scanf("%d",&a)
#define LL(a)           ((a)<<1)
#define RR(a)           (((a)<<1)+1)
#define SZ(a)           ((int)a.size())
#define PP(n,m,a)       puts("---");FF(i,n){FF(j,m)cout << a[i][j] << ' ';puts("");}
#define pb              push_back
#define CL(Q)           while(!Q.empty())Q.pop()
#define MM(name,what)   memset(name,what,sizeof(name))
#define read            freopen("in.txt","r",stdin)
#define write           freopen("out.txt","w",stdout)

const int inf = 0x3f3f3f3f;
const i64 inf64 = 0x3f3f3f3f3f3f3f3fLL;
const double oo = 10e9;
const double eps = 10e-10;
const double pi = acos(-1.0);

int k,n;
vector<int>v;

inline int head(int x)
{
    return x/1000;
}

int find()
{
    int ans=3;
    int line=1;
    int temp=head(v[0]);
    for(int i=1;i<v.size();i++)
    {
        if(temp!=head(v[i]))
        {
            ans++;
            line = 1;
            temp = head(v[i]);
        }
        else
        {
            line++;
            if(line > k)
            {
                ans++;
                line=1;
            }
        }
    }
    return ans;
}

int main()
{
    cin>>k;
    cin>>n;
    int temp;
    for(int i=1;i<=n;i++)
    {
        cin>>temp;
        v.push_back(temp);
    }
    sort(v.begin(),v.end());
    cout<<find()<<endl;
    return 0;
}