#include <bits/stdc++.h>
#define Loop(x,l,r) for (ll x = (l); x < (r); ++x)
#define LoopR(x,l,r) for (ll x = (r)-1; x >= (l); --x)
typedef long long ll;
typedef std::pair<int, int> pii;
typedef std::pair<ll , ll > pll;
using namespace std;
const int N = 200'010;
int a[N], b[N];
int n;
__attribute__((optimize("O3,unroll-loops"),target("avx2")))
void up(int x, int y)
{
Loop (i,0,n) {
a[i] ^= a[i] <= x? b[i]: 0;
a[i] ^= a[i] <= y? b[i]: 0;
}
}
int main()
{
cin.tie(0) -> sync_with_stdio(false);
int q;
cin >> n >> q;
Loop (i,0,n) {
cin >> a[i] >> b[i];
b[i] ^= a[i];
}
for (int i = 0; i < q; i += 2) {
int x, y;
cin >> x;
i+1 < q? cin >> y, 0: (y = 0);
up(x, y);
}
ll ans = 0;
Loop (i,0,n)
ans += a[i];
cout << ans << '\n';
}
