#include<cstdio>

#include<iostream>

#include<string>

#include<cstring>

#include<queue>

#include<vector>

#include<stack>

#include<vector>

#include<map>

#include<set>

#include<algorithm>

//#include<bits/stdc++.h>

using namespace std;

const int maxn = 1e3+, maxs = 2e5, bound = 1e5;

int s[maxn], f[maxn];

int dp[maxs+];

//#define LOCAL

int main()

{

#ifdef LOCAL

    freopen("in.txt","r",stdin);

#endif

    int n, c = ; cin>>n;

    int TS = , TF = ;

    for(int i = n; i--;){

        scanf("%d%d",s+c,f+c);

        if(s[c]> && f[c]>){

            TS += s[c];

            TF += f[c];

            continue;

        }

        if(s[c]<=  && f[c] <=) continue;

        c++;

    }

    memset(dp,0xc0,sizeof(dp));

    dp[bound] = ;

    for(int i = c; i--;){

        if(s[i]>){

            for(int j = maxs; j >= s[i]; j--){

                dp[j] = max(dp[j],dp[j-s[i]] + f[i]);

            }

        }

        else {

            for(int j = ; j-s[i] <= maxs; j++){

                dp[j] = max(dp[j],dp[j-s[i]] + f[i]);

            }

        }

    }

    int ans = bound;

    for(int i = bound; i <= maxs; i++){

        if(dp[i]+TF>=) ans = max(i+dp[i],ans);

    }

    printf("%d\n",ans-bound+TS+TF);

    return ;

}