#include<iostream>
#include<vector>
#include<algorithm>

using namespace std;
using ll = long long;

#include<set>
int main(){
    cin.tie(nullptr);
    ios::sync_with_stdio(false);

    int n;
    cin>>n;
    vector<ll> v(n),t(n);
    for(int i = 0;i<n;i++) cin>>v[i]>>t[i];
    ll sum = 0;
    for(int i = 0;i<n;i++) sum += v[i];
    ll right = sum + 1;
    ll left = 0;

    vector<int> idx(n);
    for(int i = 0;i<n;i++) idx[i] = i;
    sort(idx.begin(),idx.end(),[&](int i,int j){
        return t[i] + v[i] - 1 > t[j] + v[j] - 1;
    });

    auto calc = [&](ll now) {
        set<ll> all;
        all.insert(now);
        for(int i = 0;i<n;i++){
            int ni = idx[i];
            auto itr = all.upper_bound(t[ni]+v[ni]-1);
            if(itr!=all.begin()){
                itr--;
                ll use = *itr;
                if(t[ni]+v[ni]-1>=use) all.insert(use-v[ni]);
            }
        }
        return all.count(0);
    };

    while(right-left>1){
        ll mid = (right+left) / 2;
        if(calc(mid)) left = mid;
        else right = mid;
    }
    cout<<left<<endl;
}