انرژی خور

main.cpp

/// In The Name Of God
#include<bits/stdc++.h>

using namespace std;
const int MAX_N = 100010;
pair<int,int> a[MAX_N];

int main(){
    int n;
    long long k;
    cin >> n >> k;
    for(int i = 0; i < n; i++) cin >> a[i].first >> a[i].second;
    sort(a,a+n);
    for(int i = 0; i < n; i++)
        if(k >= a[i].first) /// we can eat i-th fruit
            if(a[i].second > a[i].first) /// we gain positive energy by eating this fruit
                k += a[i].second - a[i].first; /// eat -> lose a[i].first energy ans gain a[i].second
    cout << k << '\n';
}