Submission

Score: 0

User: Buktep

Problemset: ห้องสมุดเมือง 3M

Language: cpp

Time: 0.002 second

Submitted On: 2026-02-13 20:02:23

#include <bits/stdc++.h>
using namespace std;
#define int long long
#define debug(x) cerr<<#x<<" = "<<x<<"\n" 


int32_t main()
{
    cin.tie(0);ios::sync_with_stdio(0);
    int n;cin>>n;
    vector<int> v(n+1),pf(n+1);
    for(int i=1;i<=n;i++)
    {
        int x,y; cin>>x>>y;
        int r = y-x;
        // debug(r);
        v[i]=x;
        pf[i]=pf[i-1]+r;
    }
    int pos=pf[n]/2;
    int idx= lower_bound(pf.begin()+1,pf.end(), pos)-pf.begin();
    cout<<pos-pf[idx-1]+v[idx]-1;
    return 0;
}