#include <fstream>
using namespace std;
ifstream f("stergeri.in");
ofstream g("stergeri.out");

long long n, p, k, x, y, z, s, d;
long long minim=2100000000;
int main()
{
    f>>n>>p>>k;
    for(; p; --p)
    {
        f>>x>>y;
        if(x<minim) minim=x;
        z=y-x+1;
        s+=z;
    }
    s=s+minim-1;
    if(k<minim) g<<k;
    else
    {
        d=s-minim+1;
        g<<k+d;
    }
}