#include <bits/stdc++.h> using namespace std; const int maxN=100100; pair<int,int> a[maxN]; multiset<int> S; int main(){ int n; scanf("%d",&n); for(int i=0;i<n;i++)scanf("%d%d",&a[i].first,&a[i].second); sort(a,a+n); int tmp=1; for(int i=0;i<n;i++){ queue<int> Q; for (int j=tmp;j<=a[i].first;j++)S.insert(0); for (int j=0;j<a[i].second;j++){ auto P=S.begin(); Q.push(*P+1); S.erase(P); } for (int j=0;j<a[i].second;j++){ S.insert(Q.front()); Q.pop(); } tmp=a[i].first+1; } long long ans=0; for (int i=0;i<a[n-1].first;i++){ auto P=S.begin(); int x=*P; ans+=x*(x-1)/2; S.erase(P); } printf("%lld\n",ans); return 0; }

sails.cpp: In function 'int main()':
sails.cpp:8:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d",&n);
  ~~~~~^~~~~~~~~
sails.cpp:9:27: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  for(int i=0;i<n;i++)scanf("%d%d",&a[i].first,&a[i].second);
                      ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~