#include <stdio.h>

int parexpr(int dep)
{
    char c;
    int val = 0;

    do
    {
        c = getchar();

        if (c == '(')
        {
            dep++;
            if (!val)
            {
                val = 1;
            }
            val *= parexpr(dep);
        }

        if (c == ')')
        {
            dep--;
            return val + 1;
        }
    } while (dep && c != '\n');

    return val;
}

int main(void)
{
    int  n;
    int  cookies = 0;
    char seq[2] = "\0\0";

    scanf("%d ", &n);
    cookies = parexpr(NULL);

    printf("%d\n", cookies);

    return 0;
}