# include <stdio.h>
int a[100000],b[100000],n,m,k,l,i,j,aux;
int main ()
{
freopen ("stergeri.in","r",stdin);
freopen ("stergeri.out","w",stdout);
scanf ("%i%i%i",&n,&m,&k);

for (i=1;i<=m;i++)
scanf ("%i%i",&a[i],&b[i]);

      for (i=1;i<m;i++)
      for (j=i+1;j<=m;j++)
      if (a[i]>a[j])
      {
      aux=a[i];
      a[i]=a[j];
      a[j]=aux;
      aux=b[i];
      b[i]=b[j];
      b[j]=aux;
      }

   i=1;
   while (a[i]<=k && i<=m)
   {
   k=k+((b[i]-a[i])+1);
   i++;
   }


   printf ("%i",k);
   return 0;
   }