# include <stdio.h>
long int a[5000],b[5000],i,j,m,n,k,aux,y,x,n2;
int main ()
{
freopen ("stergeri.in","r",stdin);
freopen ("stergeri.out","w",stdout);
scanf ("%li",&n);
scanf ("%li",&m);
scanf ("%li",&k);
for (j=0;j<m;j++)
{
scanf ("%li",&x);
scanf ("%li",&y);
if (k>x)
k=k+(y-x+1);
else
{
a[i]=x;
b[i]=y;
i++;
}
}
n2=i;
for (i=0;i<n2-1;i++)
for (j=i+1;j<n2;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<n2;i++)
if (a[i]<k)
k=k+(b[i]-a[i]+1);
else
break;
printf ("%li",k);
return 0;
}