한 번만 경보가 닿는 칸

#include <iostream>
#include <vector>
using namespace std;

int solution(int rows, int cols, vector<vector<int>> alarms) {
    vector<vector<int>> count(rows, vector<int>(cols, 0));
    int dr[5] = {0, -1, 1, 0, 0};
    int dc[5] = {0, 0, 0, -1, 1};
    for (const vector<int>& alarm : alarms) {
        for (int d = 0; d < 5; ++d) {
            int nr = alarm[0] + dr[d], nc = alarm[1] + dc[d];
            if (nr > 0 && nr < rows && nc >= 0 && nc < cols) ++count[nr][nc];
        }
    }
    int answer = 0;
    for (const vector<int>& row : count)
        for (int value : row) if (value == 1) ++answer;
    return answer;
}
int main() {
    int rows, cols, n; cin >> rows >> cols >> n;
    vector<vector<int>> alarms(n, vector<int>(2));
    for (int i = 0; i < n; ++i) cin >> alarms[i][0] >> alarms[i][1];
    cout << solution(rows, cols, alarms) << '\n';
    return 0;
}