#include <bits/stdc++.h>

using namespace std;

inline int read() {
    int x = 0;
    char c = getchar();
    bool flag = 0;
    while (c < '0' || c > '9') {
        if (c == '-')flag = 1;
        c = getchar();
    }
    while (c >= '0' && c <= '9') {
        x = (x + (x << 2) << 1) + c - '0';
        c = getchar();
    }
    return flag ? -x : x;
}

int n, m, ttime = 0, tot = 0;
//ttime记录总时间,tot记录答案
int ans1, ans2, cnt1 = 1, cnt2 = 1, t1, t2;
//ans表示两人的路程，cnt表示当前的阶段,t表示状态转移的时间点
struct ingredient {
    int v, t;
} n1[1005], m1[1005];

bool judge(int x, int y) {
    if (x > y) return 1;
    else return 0;
}//比较函数,可以知道两人的先后顺序
int main() {
    n = read(), m = read();
    for (int i = 1; i <= n; ++i)
        n1[i].v = read(), n1[i].t = read(), ttime += n1[i].t;
    for (int i = 1; i <= m; ++i)
        m1[i].v = read(), m1[i].t = read();
    bool flag;//记录两人的先后顺序
    if (n1[1].v > m1[1].v) flag = 1;
    else flag = 0;
    t1 = n1[1].t, t2 = m1[1].t;//初始化
    for (int i = 1; i <= ttime; ++i)//枚举每一秒的状态
    {
        ans1 += n1[cnt1].v;
        ans2 += m1[cnt2].v;//通过的总路程
        if (judge(ans1, ans2) != flag) tot++, flag = !flag;
        //如果两人先后发生变化，记录下当前状态，更新答案
        if (i == t1) cnt1++, t1 += n1[cnt1].t;
        if (i == t2) cnt2++, t2 += m1[cnt2].t;
        //各自进入下一状态
    }
    cout << tot << endl;
}