import java.util.Scanner;

public class Main {
    Scanner sc = new Scanner(System.in);
    int cnt;
    int za;
    int zb;
    int[] sita;
    public static void main(String[] args) {
        new Main().solve();
    }

    void solve() {
        cnt = sc.nextInt();
        sita = new int[cnt];
        for(int i = 0; i < cnt; i++) {
            sita[i] = sc.nextInt();
        }
        for(int i = 0; i < cnt - 1; i++) {
            za = za + sita[i];
        }

        for(int i = 1; i < cnt; i++) {
            zb = zb + sita[i];
        }
        System.out.println(zb + "/" + za);
    }
}