#include <iostream>
using namespace std;

int main() {
    int weight;
    cin >> weight;
    int cost;
    if (weight < 10) {
        cost = weight * 3;
    } else {
        cost = 10 * 2 + (weight - 10) * 1;
    }
    cout << cost << endl;
    return 0;
}

#include using namespace std; int main(){ int a; cin>>a; if(a<10){ cout<<a*3; }else if(a>=10){ cout<<20+(a-10)*1; }

return 0;

}

AC的能不能发一下题解鸭