cf 1322A
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <cmath>
#include <iostream>
#include <iomanip>
#include <string>
#include <algorithm>
#include <stack>
#include <queue>
#include <set>
#include <vector>
#include <map>
#define INF 0x3f3f3f3f
#define LINF 0x3f3f3f3f3f3f3f3f
#define ll long long
#define ull unsigned long long
#define uint unsigned int
#define l(x) ((x)<<1)
#define r(x) ((x)<<1|1)
#define lowbit(x) ((x)&(-(x)))
#define ms(a,b) memset(a,b,sizeof(a))
#define NSYNC std::ios::sync_with_stdio(false);std::cin.tie(0);std::cout.tie(0);
using namespace std;
char str[1111111];
int val,len, ans,n;
int main() {
ans = val = len = 0;
scanf("%d", &n);
scanf("%s", str);
for (int i = 0; i < n; i++) {
len++;
if (str[i] == '(') {
val++;
if (val == 0) {
ans += len;
len = 0;
}
}
else val--;
if (val == 0) len = 0;
}
if (val != 0) {
printf("-1\n");
return 0;
}
printf("%d\n", ans);
return 0;
}