#include <fstream>

using namespace std;

int n,k,m;

int main()
{
    int i,x,y,dif=0;
    ifstream fin("stergeri.in");
    fin>>n>>m>>k;
    for(i=1;i<=m;i++)
    {
        fin>>x>>y;
        dif+=y-x+1;
    }
    fin.close();
    ofstream fout("stergeri.out");
    fout<<k+dif<<"\n";
    fout.close();
    return 0;
}