#include<iostream>
using namespace std;
int n,m,a[1000011],b[1000011],ans;
int l1,l2;
int main(){
	int v,t;
	cin>>n>>m;
	for(int i=1;i<=n;i++){
		cin>>v>>t;
		for(int j=1;j<=t;j++){
			a[++l1]+=a[l1-1]+v;
		}
	}
	for(int i=1;i<=m;i++){
		cin>>v>>t;
		for(int j=1;j<=t;j++){
			b[++l2]+=b[l2-1]+v;
		}
	}
	int k=2;
	bool r=(a[1]>b[1]);
	while(a[k]>a[k-1]&&b[k]>b[k-1]){
		if(r!=(a[k]>b[k])) r=(a[k]>b[k]),ans++;
		k++;
	}
	cout<<ans;
	return 0;
}