题解 | #数位dp？#

using namespace std;
int main(){
    int n;
    int count = 0;
    int first_bit = 0;
    int judge = 0;
    cin>>n;
    int tep1 = n;
    while (tep1>0){         //取它是几位数
        first_bit++;
        tep1 /=10;
    }
    tep1 = n;

    for(int i=0;i<first_bit;i++){          //删除最后一位奇数
        if(tep1%2!=0){
            count++;
        } else {
            break;
        }
        tep1 /=10;
    }
    tep1 = n;

   for(int i=0;i<first_bit-1;i++){             //取第一位数
       tep1 /=10;
   }
   judge = tep1;

   if(judge==0){
       count++;
   }



    if(judge!=0&&n%2==0){               //判断
        cout<<"0";
    }
    else{
        cout<<count;
    }









    return 0;

}