#pragma GCC optimize(2)

#pragma GCC optimize(3)

#pragma GCC optimize(4)

#include <algorithm>

#include  <iterator>

#include  <iostream>

#include   <cstring>

#include   <cstdlib>

#include   <iomanip>

#include    <bitset>

#include    <cctype>

#include    <cstdio>

#include    <string>

#include    <vector>

#include     <stack>

#include     <cmath>

#include     <queue>

#include      <list>

#include       <map>

#include       <set>

#include   <cassert>

using namespace std;

#define lson (l , mid , rt << 1)

#define rson (mid + 1 , r , rt << 1 | 1)

#define debug(x) cerr << #x << " = " << x << "\n";

#define pb push_back

#define pq priority_queue

typedef long long ll;

typedef unsigned long long ull;

typedef long double ld;

//typedef __int128 bll;

typedef pair<ll ,ll > pll;

typedef pair<int ,int > pii;

typedef pair<int,pii> p3;

//priority_queue<int> q;//这是一个大根堆q

//priority_queue<int,vector<int>,greater<int> >q;//这是一个小根堆q

#define fi first

#define se second

//#define endl '\n'

#define boost ios::sync_with_stdio(false);cin.tie(0)

#define rep(a, b, c) for(int a = (b); a <= (c); ++ a)

#define max3(a,b,c) max(max(a,b), c);

#define min3(a,b,c) min(min(a,b), c);

const ll oo = 1ll<<;

const ll mos = 0x7FFFFFFF;  //

const ll nmos = 0x80000000;  //-2147483648

const int inf = 0x3f3f3f3f;

const ll inff = 0x3f3f3f3f3f3f3f3f; //

const int mod = 1e9;

const double esp = 1e-;

const double PI=acos(-1.0);

const double PHI=0.61803399;    //黄金分割点

const double tPHI=0.38196601;

template<typename T>

inline T read(T&x){

    x=;int f=;char ch=getchar();

    while (ch<''||ch>'') f|=(ch=='-'),ch=getchar();

    while (ch>=''&&ch<='') x=x*+ch-'',ch=getchar();

    return x=f?-x:x;

}

inline void cmax(int &x,int y){if(x<y)x=y;}

inline void cmax(ll &x,ll y){if(x<y)x=y;}

inline void cmin(int &x,int y){if(x>y)x=y;}

inline void cmin(ll &x,ll y){if(x>y)x=y;}

/*-----------------------showtime----------------------*/

            const int maxn = ;

            struct node{

                ll id;

                int val;

            }a[maxn];

            bool cmp(node a,node b){

                return a.val > b.val;

            }

            ll p[];

            bool check(ll x){

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

                    if((x & (1ll << i) ) > )

                    {

                        if(p[i] >-) x ^= p[i];

                        else {

                            p[i] = x;

                            return true;

                        }

                    }

                }

                return false;

            }

int main(){

            memset(p, -, sizeof(p));

            int n;  scanf("%d", &n);

            for(int i=; i<=n; i++) {

                scanf("%lld%d", &a[i].id, &a[i].val);

            }

            sort(a+, a++n,cmp);

            int sum = ;

            for(int i=; i<=n; i++) {

                if(check(a[i].id)) sum += a[i].val;

            }

            printf("%d\n", sum);

            return ;

}