import java.io.*; import java.util.*; import java.math.*; class Main { public static void out (Object o) { System.out.println(o); } public static void main (String[] args) throws IOException { BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); int n = Integer.parseInt(br.readLine()); BigDecimal ans = BigDecimal.ZERO; BigDecimal two = BigDecimal.valueOf(2); BigDecimal m2 = BigDecimal.valueOf(10000000000L); BigDecimal m = BigDecimal.valueOf(1000000007); for (int i = 0; i < n; i++) { String[] line = br.readLine().split(" "); int len = line[1].length(); line[1] = len > 10 ? line[1].substring(len - 10 , len) : line[1]; BigDecimal c = new BigDecimal(line[0]).divide(two).setScale(0 , RoundingMode.CEILING).remainder(m2); BigDecimal d = new BigDecimal(line[1]); out(c + " , " + d); ans = ans.add(c.multiply(d).remainder(m)); } out(ans); } }