#include <stdio.h>
#include <stdlib.h>
int x[100001],y[100001];
int main()
{
    int n,m,k,i,rez,r;
    freopen("stergeri.in","r",stdin);
    freopen("stergeri.out","w",stdout);
    scanf("%d%d%d",&n,&k,&r);
    for(i=1; i<=n; i++)
        scanf("%d%d",&x[i],&y[i]);
    rez=r;
    for(i=n; i>0; i--)
        if(x[i]<=rez)
            rez+=(y[i]-x[i]+1);
    printf("%d\n",rez);

    return 0;
}