#include <iostream>
#include <fstream>
using namespace std;
ifstream in("stergeri.in");
ofstream out("stergeri.out");
int a1[100005];
int b1[100005];
int main()
{
    int n, m, k;
    in >> n >> m >> k;
    for(int i = 1; i <= m; i ++)
         in >> a1[i] >> b1[i];
    int poz = k;
    for(int i = m; i >= 1; i --)
        if(b1[i] >= k)
            poz += (b1[i] - a1[i] + 1);
    out << poz;
    return 0;
}