#include <bits/stdc++.h>
using namespace std;
long long n,cb,xl,i,j,s,mg,a[100010],x,y,b,c,d,ma,aaa,st;
bool fl;
int main(){
	ios::sync_with_stdio(false);
	cin.tie(0);
	cout.tie(0);
	cin>>n>>cb>>xl;
	i=1;
	b=cb;
	c=xl; 
	a[cb]=xl;
	while(cin>>x>>y){
		if(x==-1&&y==-1) break;
		a[x]=y;
		for(i=b+1;i<x;i++){
			a[i]=c-(c-y)/(x-b)*(i-b); 
		}
		c=y;
		b=x;
	}
	cin>>mg;
	while(c>mg){
		b++;
		c-=mg;
		a[b]=c;
	}
	for(i=0;i<=100000;i++){
		ma=-1;
		for(j=cb+1;j<=b;j++){
			aaa=(j-cb+i)*a[j];
			if(aaa>ma){
				st=j;
				ma=aaa;
			}
		}
		if(st==n){
			cout<<i;
			fl=1;
			break;
		}
		ma=-1;
		for(j=cb+1;j<=b;j++){
			aaa=(j-cb-i)*a[j];
			if(aaa>ma){
				st=j;
				ma=aaa;
			}
		}
		if(st==n){
			cout<<i*(-1);
			fl=1;
			break;
		}
	}
	if(fl==0) printf("NO SOLUTION");
	return 0;
}