这里是可爱的妹子！！！90分 两个点WA求助qwq

这是怎么回事啊QAQ，从上午调到下午了TAT

#include <bits/stdc++.h>
using namespace std;
const int N=(int)2e5+50;
int n,m,l=1<<30,r=-1<<30;
long long S,ans=1e18,Y,sum;
struct node{
    int w,v;
}per[N];
struct sid{
    int L,R;
}sec[N];
int pre_v[N],pre_n[N];
bool isok(int W){
    Y=0,sum=0;
    memset(pre_v,0,sizeof(pre_v));memset(pre_n,0,sizeof(pre_n));
    for(int i=1;i<=n;i++){
        if(per[i].w>=W){pre_v[i]=pre_v[i-1]+per[i].v;pre_n[i]=pre_n[i-1]+1;}
        else{pre_v[i]=pre_v[i-1];pre_n[i]=pre_n[i-1];}
    }
    for(int i=1;i<=m;i++){Y+=(pre_n[sec[i].R]-pre_n[sec[i].L-1])*(pre_v[sec[i].R]-pre_v[sec[i].L-1]);}
    sum=llabs(Y-S);
    if(Y>S) return true;
    else return false;
}
inline int read(){
    register int cnt=0,f=1;char c=getchar();
    while(!isdigit(c)){if(c=='-')f=-f;c=getchar();}
    while(isdigit(c)){cnt=(cnt<<3)+(cnt<<1)+(c^48);c=getchar();}
    return cnt*f;
}
int main(){
//  freopen("testdata (3).in","r",stdin);
    n=read(),m=read();scanf("%lld",&S);
    for(int i=1;i<=n;i++){
        per[i].w=read();per[i].v=read();
        l=min(l,per[i].w);r=max(r,per[i].w);
    }
    for(int i=1;i<=m;i++){
        sec[i].L=read(),sec[i].R=read();
    }
    l=l-1,r=r+2;
    while(l<=r){
        int mid=(l+r)>>1;
        if(isok(mid))   l=mid+1;
        else    r=mid-1;
        ans=min(ans,sum);
    }
    printf("%lld",ans);
    return 0;
}