1. #include <cstdio>
    2. #include <algorithm>
    3. #include <cstring>
    4. #include <cmath>
    5. #include <cstdlib>
    6. using namespace std;
    7. const int N = 1e6+10020;
    8. char S[N];
    9. int Sum[N],Minn[N];
    11. signed main()
    12. {
    13. #ifdef TSUKIAKIOI
    14.     freopen("data.in","r",stdin);
    15. #endif
    16.     int n;scanf("%d",&n);
    17.     scanf("%s",S);
    18.     int len = n;
    19.     for(int i=1;i<=len;++i)
    20.         Sum[i] = (S[i-1] == ')' ? -1 : 1) + Sum[i-1];
    21.     int tot = 0;
    22.     Minn[len+1]=1e9;
    23.     for(int i=len;i;--i)
    24.         Minn[i] = min(Minn[i+1],Sum[i]),
    25.         tot += S[i-1] == ')' ? 1 : -1;
    26.     if(tot != 2 && tot != -2)
    27.         return puts("0"),0;
    28.     int ans = 0;
    29.     int minn = 0;
    30.     for(int i=1;i<=n;++i){
    31.         if(tot == 2 && S[i-1] == '(') goto end;
    32.         if(tot == -2 && S[i-1] == ')') goto end;
    33.         if(minn < 0)
    34.             break;
    35.         if(Minn[i] >= -tot){
    36. #ifdef HJWWWW
    37.             printf("%d\n",i);
    38. #endif
    39.             ans++;
    40.         }
    41. end:
    42.         minn = min(minn,Sum[i]);
    43.     }
    44.     printf("%d\n",ans);
    45.     return 0;
    46. }