为什么错了

#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
ll mid,start,end,ans,n,m,s,w[10000],v[10000],l[10000],r[10000],sum[10000],sumv[10000];
void work(ll s)
{sum[0]=0ll;
    sumv[0]=0ll;
    for(int i=1;i<=n;i++)
    if(w[i]>=s)
    {
    sum[i]=sum[i-1]+1;
    sumv[i]=sumv[i-1]+v[i];
    }
    else 
    {sum[i]=sum[i-1];
    sumv[i]=sumv[i-1];
    }
}
ll qxh(ll mid)
{ 
ll ss=0;
for(int i=1;i<=m;i++)
 ss=(sum[r[i]]-sum[l[i]-1])*(sumv[r[i]]-sumv[l[i]-1]);
 return ss;
}
ll bijiao(ll a)
{
    if(a>0) return a;
    else return -a;
}
int main()
{   
ans=99999999999;
start=0ll;end=0ll;
    cin>>n>>m>>s;
    for(int i=1;i<=n;i++)
    {cin>>w[i]>>v[i];
    if(w[i]>end) end=w[i]; 
    }
    for(int i=1;i<=m;i++)
    cin>>l[i]>>r[i];
    while(start<=end)
    {
        mid=(start+end)/2;
        work(mid);
        ll t=qxh(mid);
        if(bijiao(t-s)<ans)
        ans=bijiao(t-s);
        if(ans==0) break;
        if(s<t) start=mid+1;
        else end=mid-1;
    }
    cout<<ans<<endl;
    return 0;
}