import java.io.BufferedReader;
import java.io.InputStreamReader;

public class Main {
	public static void main(String[] args) throws Exception {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		int n = Integer.parseInt(br.readLine());
		int[] a = new int[n];
		int[] b = new int[n];
		for (int i = 0; i < n; i++) {
			String[] sa = br.readLine().split(" ");
			a[i] = Integer.parseInt(sa[0]);
			b[i] = Integer.parseInt(sa[1]);
		}
		br.close();

		long[] a2 = new long[n + 1];
		long[] b2 = new long[n + 1];
		for (int i = n - 1; i >= 0; i--) {
			a2[i] = a2[i + 1] + a[i];
			b2[i] = b2[i + 1] + b[i];
		}

		long ans = 0;
		for (int i = 0; i < n; i++) {
			long v1 = a[i] * b2[i + 1];
			long v2 = b[i] * a2[i + 1];
			ans += Math.max(v1, v2);
		}
		System.out.println(ans);
	}
}