题目：P3056 [USACO12NOV] Clumsy Cows S

#include<bits/stdc++.h>
using namespace std;
int sum,ans;
char a[100010];
int main(){
    freopen("P3056_2.in","r",stdin);
    scanf("%s",&a);
    for(int i=0;i<strlen(a);i++){
        if(a[i]=='(')sum++;
        else if(a[i]==')'&&sum==0){
            ans++;
            sum++;
        }else sum--;
    }
    ans+=(sum+1)/2;
    printf("%d",ans);
    return 0;
}
//()(())()(()())