#include <iostream>
#include <vector>
#include <string>
#include <algorithm>
#include <utility>
#include <stack>
#include <functional>
#include <queue>
#include <cmath>
#include <set>
#include <map>

#define rep(i,j,k) for(int i=(int)j;i<(int)k;i++)
#define Sort(x) sort((x).begin(),(x).end())
#define all(x) (x).begin(),(x).end()
#define fi first
#define se second
#define vi vector<int>
#define INF (int)1e933
#define INFL 1e18
//define MOD 1e9+7
#define pb push_back
#define MP make_pair
typedef long long ll;
typedef std::pair<int,int> pii;
int dx[4]={0,1,0,-1},dy[4]={1,0,-1,0};

using namespace std;

int main() {
    ll MOD=1e9+7;
    int n; cin>>n;
    ll ans=0;
    rep(i,0,n){
        ll x,y;
        cin>>x>>y;
        if(x%2){
            x=x/2+1;
        }else x/=2;
        if(x>MOD)x%=MOD;
        if(y>MOD)y%=MOD;
        
        ans+=(x*y)%MOD;
        if(ans>MOD)ans%=MOD;
    }
    cout<<ans<<endl;
    return 0;
}