AOJ1297.cpp

#include <iostream>
#include <vector>
#include <string>
#include <cstring>
#include <map>
#include <queue>
#include <algorithm>

#define REP(i,n) for(int i=0;i<(int)(n);i++)
#define ALL(x) (x).begin(),(x).end()

using namespace std;

int main() {
  int t, n;
  while (cin >> n, n) {
    queue<pair<int,pair<int,int>>> q1, q2;
    vector<pair<int,int>> dat(n);
    REP(i,n) cin >> dat[i].first >> dat[i].second;
    sort(ALL(dat));
    REP(i,n) q1.push({dat[i].first, dat[i]});
    for (t = 0; !q1.empty() || !q2.empty(); t++) {
      vector<pair<int,pair<int,int>>> a, b;
      while (!q1.empty() && q1.front().first <= t) {
        a.push_back(q1.front());
        q1.pop();
      }
      REP(i,a.size()) a[i].first = t + a[i].second.first;
      sort(ALL(a));
      REP(i,a.size()) q2.push(a[i]);
      
      while (!q2.empty() && q2.front().first <= t) {
        b.push_back(q2.front());
        q2.pop();
      }
      REP(i,b.size()) {
        b[i].first = t + b[i].second.first;
        b[i].second.second--;
      }
      sort(ALL(b));
      REP(i,b.size()) if (b[i].second.second > 0) q1.push(b[i]);
    }
    cout << t - 1 << endl;
  }
  return 0;
}