import std.algorithm, std.conv, std.range, std.stdio, std.string;

const auto p = 10^^9 + 7;
alias FactorRing!p mint;

void main()
{
  auto n = readln.chomp.to!size_t;

  auto r = mint(0);
  foreach (_; n.iota) {
    auto rd = readln.split.to!(long[]), c = rd[0], d = rd[1];
    r += mint((c + 1) / 2) * mint(d);
  }

  writeln(r.toInt);
}

struct FactorRing(int m)
{
  long v;

  @property int toInt() { return v.to!int; }
  alias toInt this;

  this(T)(T _v) { v = mod(_v); }

  ref FactorRing!m opAssign(int _v)
  {
    v = mod(_v);
    return this;
  }

  pure auto mod(long _v) const { return _v > 0 ? _v % m : ((_v % m) + m) % m; }

  pure auto opBinary(string op: "+")(int rhs) const { return FactorRing!m(v + rhs); }
  pure auto opBinary(string op: "-")(int rhs) const { return FactorRing!m(v - rhs); }
  pure auto opBinary(string op: "*")(int rhs) const { return FactorRing!m(v * rhs); }

  pure auto opBinary(string op)(FactorRing!m rhs) const
    if (op == "+" || op == "-" || op == "*") { return opBinary!op(rhs.v); }

  auto opOpAssign(string op: "+")(int rhs) { v = mod(v + rhs); }
  auto opOpAssign(string op: "-")(int rhs) { v = mod(v - rhs); }
  auto opOpAssign(string op: "*")(int rhs) { v = mod(v * rhs); }

  auto opOpAssign(string op)(FactorRing!m rhs)
    if (op == "+" || op == "-" || op == "*") { return opOpAssign!op(rhs.v); }
}