#include<bits/stdc++.h>
using namespace std;
struct Posto{
	double distance;
	double rate;
}po[1000];
int main(){
	double D1,C,D2,P,n,v=0,sur=0,om,sum=0;
	cin>>D1>>C>>D2>>P>>n;
	int i;
	for(i=1;i<=n;i++)
	{
		cin>>po[i].distance>>po[i].rate;
	}
	i=1;
	om=C;
	while(om!=0)
	{
		sur=om-po[i].distance/D2;
		om-=sur;
		if((om+sur)*D2<po[i].distance-po[i-1].distance)
		{
			cout<<"No Solution";
			break;
		}
		v=sur*po[i].rate;
		sum+=v;
	}
	printf("%.2lf",sum);
	return 0;
}

帮帮我。