# include <stdio.h>
int a[100010],b[100010],n,m,k,i,ok,aux,j;
int main ()
{
freopen ("stergeri.in","r",stdin);
freopen ("stergeri.out","w",stdout);
scanf ("%i",&n);
scanf ("%i",&m);
scanf ("%i",&k);
for (i=0;i<m;i++)
scanf ("%i%i",&a[i],&b[i]);
for (i=0;i<m-1;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;
}
for (i=0;i<m;i++)
if (a[i]<k)
k=k+(b[i]-a[i])+1;
else
break;
printf ("%i",k);
return 0;
}