All pair product sum

/* All pair product sum
Sample Input 0

3 2
1 2 3
4 5
Sample Output 0

54 */

#include<stdio.h>

int main()
{
    int n, m;
    scanf("%d %d", &n, &m);

    int i, j, a[n], b[m];
    for(i = 0; i < n; i++) scanf("%d", &a[i]);
    for(j = 0; j < m; j++) scanf("%d", &b[j]);

    long long s = 0, ans = 0;
    for(i = 0; i < n; i++)
    {
        s += a[i];
    }
    //printf("%lld\n", s);
    for(j = 0; j < m; j++)
    {
        ans += s * b[j];
    }
    printf("%lld\n", ans);
}