#include<stdio.h>
FILE*f=fopen("stergeri.in","r");
FILE*g=fopen("stergeri.out","w");
long x,y,n,m,p,k,s;
void update()
    {
     if(x<=k)
       {
        if(y<=k) s+=(y-x+1)+p,p=0;
        else
          {
           p+=y-k;
           s=s+(k-x+1)+p;
           p=0;
          }
        }
     else p+=y-x+1;
    }
int main()
   {
    fscanf(f,"%ld %ld %ld",&n,&m,&k);
    s=k;
    for(long i=1;i<=m;++i)
       {
        fscanf(f,"%ld %ld",&x,&y);
        update();
       }
    fprintf(g,"%ld\n",s);
    return 0;
   }