rollercoaster3.cpp

// NOTE: it is recommended to use this even if you don't understand the following code.

#include <fstream>
#include <iostream>
#include <string>
#include <vector>

using namespace std;

int main() {
    // uncomment the two following lines if you want to read/write from files
    // ifstream cin("input.txt");
    // ofstream cout("output.txt");

    int N;
    cin >> N;

    string S;
    cin >> S;

    int K = 0;


    // INSERT YOUR CODE HERE
    int sum = 0;
    int H_count = 0;
    for (int i=0; i<N; i++) {
        if (S[i] == 'D') sum += 9;
        else if (S[i] == 'B') sum += 10;
        else if (S[i] == 'U') sum -= 11;
        else if (S[i] == 'H') H_count ++;

        if (sum <= 0) {
            while (H_count && sum <= 0) {
                sum += 10;
                K ++;
                H_count --;
            }
            if (sum <= 0) {
                K = -1;
                break;
            }
        }
    }


    cout << K << endl;

    return 0;
}