#include <bits/stdc++.h> using namespace std; int main(){ int n; int y; cin >> n; cin >> y; vector<pair<int,int>> nums(n); for(int i=0;i<n;i++){ cin >> nums[i].first >> nums[i].second; } sort(nums.begin(),nums.end()); int ans = 0; for(int i=0;i<n;i++){ if(nums[i].second != 0){ ans += nums[i].second; for(int j =i+1;j<=n;j++){ if(nums[j].first < 2*y+nums[i].first){ nums[j].second = nums[j].second <= nums[i].second ? 0:nums[j].second-nums[i].second; } } } } cout << ans << endl; system("pause"); return 0; }