#include <bits/stdc++.h>
using namespace std;
using ll = long long int;

int main(){
  int N;
  cin>>N;
  vector<vector<ll>> V(N+1);
  for(int i=0;i<N+1;i++){
    V[i] = {};
  }
  for(int i=0;i<N;i++){
    ll X;
    int C;
    cin>>X>>C;
    V[C].push_back(X);
  }
  
  vector<pair<ll,ll>> pv={};
  int lpv=0;
  for(int i=0;i<N+1;i++){
    int l = V[i].size();
    if(l == 0)continue;
    pair<ll,ll> p;
    sort(V[i].begin(),V[i].end());
    p.first=V[i][0];
    p.second=V[i][l-1];
    pv.push_back(p);
    lpv++;
  }
  
  ll dp[lpv][2];
  dp[0][0] = abs(pv[0].second) + abs(pv[0].first-pv[0].second);
  dp[0][1] = abs(pv[0].first) + abs(pv[0].first-pv[0].second);
  for(int i=1;i<lpv;i++){
    dp[i][0] = min(dp[i-1][0] + abs(pv[i].second-pv[i-1].first) 
                   + abs(pv[i].first-pv[i].second),
                   dp[i-1][1] + abs(pv[i].second-pv[i-1].second)
                   + abs(pv[i].first-pv[i].second) );
    dp[i][1] = min(dp[i-1][0] + abs(pv[i].first-pv[i-1].first) 
                   + abs(pv[i].first-pv[i].second),
                   dp[i-1][1] + abs(pv[i].first-pv[i-1].second) 
                   + abs(pv[i].first-pv[i].second) );
  }
  ll ans = min(dp[lpv-1][0] + abs(pv[lpv-1].first),
               dp[lpv-1][1] + abs(pv[lpv-1].second) );
  cout << ans << endl;
}
#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ld = long double;
// --------------------------------------------------------
template<class T> bool chmax(T& a, const T b) { if (a < b) { a = b; return 1; } return 0; }
template<class T> bool chmin(T& a, const T b) { if (b < a) { a = b; return 1; } return 0; }
#define FOR(i,l,r) for (ll i = (l); i < (r); ++i)
#define RFOR(i,l,r) for (ll i = (r)-1; (l) <= i; --i)
#define REP(i,n) FOR(i,0,n)
#define RREP(i,n) RFOR(i,0,n)
#define ALL(c) (c).begin(), (c).end()
#define RALL(c) (c).rbegin(), (c).rend()
#define SORT(c) sort(ALL(c))
#define RSORT(c) sort(RALL(c))
#define MIN(c) *min_element(ALL(c))
#define MAX(c) *max_element(ALL(c))
#define SUMLL(c) accumulate(ALL(c), 0LL)
#define COUNT(c,v) count(ALL(c),(v))
#define SZ(c) ((ll)(c).size())
#define BIT(b,i) (((b)>>(i)) & 1)
#define PCNT(b) __builtin_popcountll(b)
#define CIN(c) cin >> (c)
#define COUT(c) cout << (c) << '\n'
#define debug(x) cerr << "l." << __LINE__ << " : " << #x << " = " << (x) << '\n'
ll llceil(ll a, ll b) { return (a + b - 1) / b; }
string toupper(const string& S) { string T(S); REP(i,SZ(T)) T[i] = toupper(T[i]); return T; }
string tolower(const string& S) { string T(S); REP(i,SZ(T)) T[i] = tolower(T[i]); return T; }
using P = pair<ll,ll>;
using VP = vector<P>;
using VVP = vector<VP>;
using VS = vector<string>;
using VVS = vector<VS>;
using VLL = vector<ll>;
using VVLL = vector<VLL>;
using VVVLL = vector<VVLL>;
using VB = vector<bool>;
using VVB = vector<VB>;
using VVVB = vector<VVB>;
using VD = vector<double>;
using VVD = vector<VD>;
using VVVD = vector<VVD>;
using VLD = vector<ld>;
using VVLD = vector<VLD>;
using VVVLD = vector<VVLD>;
static const double EPS = 1e-10;
static const double PI  = acos(-1.0);
static const ll MOD = 1000000007;
// static const ll MOD = 998244353;
static const ll INF = (1LL << 62) - 1;  // 4611686018427387904 - 1
// --------------------------------------------------------
// #include <atcoder/all>
// using namespace atcoder;


int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout << fixed << setprecision(15);

    ll N; cin >> N;
    VLL X(N),C(N); REP(i,N) cin >> X[i] >> C[i];

    map<ll,VLL> mp;
    // mp[0].push_back(0);
    mp[N+1].push_back(0);
    REP(i,N) mp[C[i]].push_back(X[i]);

    ll M = SZ(mp);
    VVLL dp(M+1,VLL(2,INF));
    dp[0][0] = 0;
    ll i = 1;
    VLL prev = {0,0};
    for (auto& [_, X] : mp) {
        ll L = INF, R = -INF;
        for (ll x : X) { chmin(L, x); chmax(R, x); }
        chmin(dp[i][0], dp[i-1][0] + llabs(prev[0] - R) + llabs(L - R));
        chmin(dp[i][0], dp[i-1][1] + llabs(prev[1] - R) + llabs(L - R));
        chmin(dp[i][1], dp[i-1][0] + llabs(prev[0] - L) + llabs(L - R));
        chmin(dp[i][1], dp[i-1][1] + llabs(prev[1] - L) + llabs(L - R));
        i++;
        prev[0] = L; prev[1] = R;
    }
    ll ans = MIN(dp[M]);
    COUT(ans);

    return 0;
}
