#include<bits/stdc++.h>
using namespace std;

void __print(int x) {cerr << x;}
void __print(long x) {cerr << x;}
void __print(long long x) {cerr << x;}
void __print(unsigned x) {cerr << x;}
void __print(unsigned long x) {cerr << x;}
void __print(unsigned long long x) {cerr << x;}
void __print(float x) {cerr << x;}
void __print(double x) {cerr << x;}
void __print(long double x) {cerr << x;}
void __print(char x) {cerr << '\'' << x << '\'';}
void __print(const char *x) {cerr << '\"' << x << '\"';}
void __print(const string &x) {cerr << '\"' << x << '\"';}
void __print(bool x) {cerr << (x ? "true" : "false");}

template<typename T, typename V>
void __print(const pair<T, V> &x) {cerr << '{'; __print(x.first); cerr << ','; __print(x.second); cerr << '}';}
template<typename T>
void __print(const T &x) {int f = 0; cerr << '{'; for (auto &i: x) cerr << (f++ ? "," : ""), __print(i); cerr << "}";}
void _print() {cerr << "]\n";}
template <typename T, typename... V>
void print(T t, V... v) {_print(t); if (sizeof...(v)) cerr << ", "; _print(v...);}
#ifndef ONLINE_JUDGE
#define debug(x...) cerr << "[" << #x << "] = ["; _print(x)
#else
#define debug(x...)
#endif

#define len(v) (int)(v).size()
#define all(v) (v).begin(),(v).end()
#define forn(i, n) for (int i=0;i<n;++i)

using val = int64_t;
using ii = pair<val,int>;

const char nl = '\n';
const int mod = 1000000007;

int main() {
  cin.tie(nullptr)->sync_with_stdio(false);

  int n;
  cin >> n;
  deque<val> a, b;
  forn (i, n) {
    val x;
    int dir;
    cin >> x >> dir;
    if (dir) a.push_back(x);
    else b.push_back(x);
  }
  val tempo = 0;
  while (!(a.empty() && b.empty())) {
    if (a.empty()) {
      if (tempo < b.front()) {
    tempo = b.front();
      }
      val q = b.front();
      b.pop_front();
      while (!b.empty() && q < tempo) {
    q = b.front();
    b.pop_front();
      }
      if (q < tempo) {
    tempo += 10;
      } else {
    if (!b.empty()) {
      tempo += b.back() - q + 10;
    } else {
      tempo += 10;
    }
      }
      break;
    } else if (b.empty()) {
      if (tempo < a.front()) {
    tempo = a.front();
      }
      val q = a.front();
      a.pop_front();
      while (!a.empty() && q < tempo) {
    q = a.front();
    a.pop_front();
      }
      if (q < tempo) {
    tempo += 10;
      } else {
    if (!a.empty()) {
      tempo += a.back() - q + 10;
    } else {
      tempo += 10;
    }
      }
      break;
    } else {
      if (a.front() < b.front()) {
    val q = a.front();
    a.pop_front();
    val diff = 0;
    if (tempo < q) {
      tempo = q;
    }
    while (!a.empty() && a.front() - q <= 10) {
      diff += max(a.front() - max(tempo, q), (val)0);
      q = a.front();
      a.pop_front();
    }
    tempo += 10 + diff;
      } else {
    val q = b.front();
    b.pop_front();
    val diff = 0;
    if (tempo < q) {
      tempo = q;
    }
    while (!b.empty() && b.front() - q <= 10) {
      diff += max(b.front() - max(tempo, q), (val)0);
      q = b.front();
      b.pop_front();
    }
    tempo += 10 + diff;
      }
    }
  }

  cout << tempo << nl;


  return 0;
}