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

enum MOD = 10^^9 + 7;

void main(){
  immutable N = readln().strip().to!int();

  long ans;
  foreach(immutable i; 0 .. N) {
    auto buf = readln().strip().split().map!(to!long)().array;
    ans += ((buf[0] + 1) / 2 % MOD) * (buf[1] % MOD);
  }

  writeln(ans);
}