#include <algorithm>
#include <cfloat>
#include <climits>
#include <cmath>
#include <complex>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <functional>
#include <iostream>
#include <map>
#include <memory>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <utility>
#include <vector>
 
using namespace std;
 
#define sz size()
#define pb push_back
#define mp make_pair
#define fi first
#define se second
#define all(c) (c).begin(), (c).end()
#define rep(i,a,b) for(int i=(a);i<(b);++i)
#define clr(a, b) memset((a), (b) ,sizeof(a))
 
#define MOD 1000000007

int main(){
  int n;
  cin>>n;
  long long ans = 0LL;
  rep(i,0,n){
    long long a;
    long long b;
    cin>>a>>b;
    a = a/2LL+a%2;
    a%=MOD;
    b%=MOD;
    ans += (a*b)%MOD;
    ans%=MOD;
  }
  cout << ans <<endl;
  return 0;
}