#include <stdio.h>   
  
int i,x,y,m,n,k,s,max1,max2;   
  
int main()   
{   
freopen("stergeri.in","r",stdin);   
freopen("stergeri.out","w",stdout);
scanf("%ld %ld %ld\n",&n,&m,&k);   
s=k;
max1=max2=0;
for (i=1;i<=m;++i)   
{ 
  scanf("%ld %ld\n",&x,&y);   
  s+=(y-x+1);
  if (y>max1)
     {
            max1=y;
            max2=x;
        }
}   
printf("%ld",s-(max1-max2)-1);   
return 0;
}