#include <stdio.h>
#include <stdlib.h>
FILE *in,*out;
int x[100001],y[100001];
int main()
{
    in = fopen("stergeri.in","r");
    out = fopen("stergeri.out","w");
    int i,n,m,k,c1,c2,j;
    fscanf(in,"%d %d %d\n",&n,&m,&k);
    for(i = 1;i <= m;i ++)
    {
        fscanf(in,"%d %d",&x[i],&y[i]);
    }
    for(i = m;i >= 1;i --)
    {
        k += y[i] - x[i] + 1;
    }
    fprintf(out,"%d",k);
    return 0;
}