#include<stdio.h>
int main()
{
    freopen("stergeri.in","r",stdin);
    freopen("stergeri.out","w",stdout);
    int n,i,k,sir,o;
    scanf("%d%d%d",&sir,&n,&o);
    int a[n],b[n];
    for(i=1;i<=n;i++)
                     scanf("%d%d",&a[i],&b[i]);
    for(i=n;i>=1;i--)
    {
                     ///if(o<b[i])
                     o=o+b[i]-a[i]+1;//((o-a[i]));
                 //    printf("%d %d %d\n",o,a[i],b[i]);
                     }
                     printf("%d",o);
                     return 0;
                     }