#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
const long long c = 100000;
const int N = 1e5+10;
ll a[N],b[N];
bool sroce[N];
int main()
{
    int n,m,t,res = 0;
    cin>>n>>m>>t;
    int cnt = 0;
    while(m--)
    {
        int ts,id;
        cin>>ts>>id;
        a[cnt++] = id*c+ts;
    }
    sort(a,a+cnt);
    for(int i =1;i<=n;i++)
    {
        for(int j = 1;j<=t;j++)
        {
            int q = i*c+j,l=0,r=cnt-1,mid = 0;
            while(l<r)
            {
                mid = l+r>>1;
                if(a[mid]>=q) r = mid;
                else l = mid + 1;
            }
            if(a[r]==q)
            {
                int count = 1;
                for(int k = r+1;k<cnt;k++)
                {
                    if(a[k]!=q) break;
                    else count++;
                }
                b[i]+=count*2;
            }
            else {if(b[i]-1>=0)b[i]-=1;}
          if(b[i]>5) sroce[i] = 1;
      if(b[i]<=3) sroce[i] = 0;
        }
    }
    for(int i = 1;i<=n;i++)
        if(sroce[i]) res++;
    cout<<res<<endl;
    return 0;
}