пример на строки №2

#include <cstdio>
#include <cstring>

#define L int(1e5 + 5)

using namespace std;

char s[L];

bool correct(char sym) {
    return (sym == ' ' || (sym >= 'a' && sym <= 'z') || (sym >= 'A' && sym <= 'Z'));
}

int main() {
    gets(s);
    int l = strlen(s), res = 0;
    bool open = false;

    for (int i = 0; i < l; i++) {
        if (s[i] == '(') {
            if (open) res++;
            open = true;
        }
        if (s[i] == ')') {
            if (open)
                open = false;
            else
                res++;
        }
        if (s[i] != '(' && s[i] != ')') {
            if (open) {
                if (!correct(s[i])) {
                    open = false;
                    res++;
                }
            }
        }
    }

    if (open) res++;

    printf("%d", res);

    return 0;
}