#include <stdio.h>

int main(){
    int N=1;
    scanf("%d", &N);
    if(N%2!=0){
        return 0;
    }
    char pom[N+1];
    for(int i=0;i<(N+1);i++){
        scanf("%c", &pom[i]);
    };
    int pom1=0;
    for(int i=0;i<=(N+1);i++){
        if(pom[i]=='('&&pom[i+1]==')'){            
            pom1++;            
        }else if(pom[i]==')'&&pom[i+1]==')'){
            pom1++;
        }
    }
    printf("%d\n", pom1);
    return 0;
}
//We tried it several times with different examples(2,4,6,8,10,12) and we got correct
// answers for each of them.  Can you clarify our issue?