#include <stdio.h>

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

    scanf("%d ", &n);
    while((seq[1] = getchar()) != '\n')
    {
        if (seq[0] == '(' && seq[1] == ')')
        {
            cookies++;
        }

        if (seq[0] == ')' && seq[1] == ')')
        {
            cookies++;
        }

        seq[0] = seq[1];
    }

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

    return 0;
}