求助大佬，反过来二分为什么会超时呢？

// Problem: P1314 [NOIP2011 提高组] 聪明的质监员
// Contest: Luogu
// URL: https://www.luogu.com.cn/problem/P1314
// Memory Limit: 125 MB
// Time Limit: 1000 ms
// Code by: ING__
// 
// Powered by CP Editor (https://cpeditor.org)

#include <iostream>
#include <cstdio>
#include <algorithm>
#include <cstring>
#include <cmath>
#include <map>
#include <vector>
#include <set>
#include <queue>
#include <stack>
#include <sstream>
#define ll long long
#define re return
#define Endl "\n"
#define endl "\n"
#define x first
#define y second

using namespace std;

typedef pair<int, int> PII;

int dx[4] = {-1,0,1,0};
int dy[4] = {0,1,0,-1};

const int N = 200010;

int n, m;
ll s;

struct nope{
    int w;
    int v;
    int id;
}a[N];

PII qj[N];

ll summ[N];
ll cnt[N];

ll gety(int W){
    ll res = 0;
    for(int i = 1; i <= n; i++){
        if(a[i].w >= W){
            summ[i] = summ[i - 1] + a[i].v;
            cnt[i] = cnt[i - 1] + 1;
        }
        else{
            summ[i] = summ[i - 1];
            cnt[i] = cnt[i - 1];
        }
    }

    for(int j = 1; j <= m; j++){
        res += (cnt[qj[j].y] - cnt[qj[j].x - 1]) * (summ[qj[j].y] - summ[qj[j].x - 1]);
    }

    return res;
}

int main(){
    scanf("%d%d%lld", &n, &m, &s);

    for(int i = 1; i <= n; i++){
        scanf("%d%d", &a[i].w, &a[i].v);
        a[i].id = i;
    }

    // sort(a + 1, a + 1 + n);

    for(int i = 1; i <= m; i++){
        scanf("%d%d", &qj[i].x, &qj[i].y);
    }

    int l = 1;
    int r = 1e6 + 1;

    while(l < r){
        int mid = (l + r) >> 1;
        if(gety(mid) >= s){ // 值如果变小
            r = mid - 1;
        }
        else{
            l = mid;
        }
    }

    printf("%lld",min(abs(s - gety(r + 1)), abs(s - gety(r))));
    re 0;
}