#include<iostream>
using namespace std;
int main(){
	long long x, n, a, b, sum = 0;
	cin >> x >> n;
	for (int i = 1; i <= n; i++){
		cin >> a >> b;
		long long p = 1;
		for (int j = 1; j <= b; j++)
			p = p * x;
		sum = sum + a * p;
	}
	cout << sum;
	return 0;
}