#include <iostream>
using namespace std;
int main() {
    int n;
    cin >> n;
    long long kq=0;
    while (n--) {
        long long a,b;
        cin >> a >> b;
        kq+=(a*b)%1000000007;
    }
    cout << kq%1000000007;
}

$\color{#1fdb91}{\texttt{C}}\color{#0aaec9}{\texttt{+}}\color{#e9418e}{\texttt{+}}$

#include <iostream>

using namespace std;

const long long MOD = 1e9+7;

int main() {

  long long n, a, b, _b=1, res=0; cin >> n;
  for (long long i=1; i<=n; ++i) {
    cin >> a >> b; _b *= b;
    res = (res + a * _b) % MOD;
  }

  cout << res;
  
}

$\\$
\begin{array}{c|c|c}\color{#ffd710}{\texttt{\{}} \color{#8655d6}{\texttt{\{}}\ \ \color{#8cdcda}{\text{Daoanhviet96}}\ \ \color{#8655d6}{\texttt{\}}} \color{#ffd710}{\texttt{\}}}\end{array}