#include<bits/stdc++.h>
using namespace std;
int main() {
    double n;
    cin >> n;
    if(n < 1) {
        cout << "y=" << fixed << setprecision(2) << n << endl;
    } else if(n >= 1 && n < 10) {
        cout << "y=" << fixed << setprecision(2) << 2 * n - 1 << endl;
    } else {
        cout << "y=" << fixed << setprecision(2) << 3 * n - 11 << endl;
    }
    return 0;
}