#include <stdio.h>

#define fin  "stergeri.in"
#define fout "stergeri.out"

long N,M,K;

long go(long lev,long p)
{
	long x,y;

	scanf("%ld%ld",&x,&y);

	if ( lev < M ) p = go(lev+1,p);

	return p + ( y - x + 1 ) *  ( ( p < x ) ? (0) : (1) );
}

int main()
{
	freopen(fin,"r",stdin);
	freopen(fout,"w",stdout);

	scanf("%ld%ld%ld",&N,&M,&K);

	printf("%ld\n",go(1,K));

	return 0;
}