#include <stdio.h>
int main() {
int n, a, b, ans;
while (scanf("%d", &n) == 1) {
a = n;
b = n;
ans = n;
while (a >= 3 || b >= 4) {
n = a / 3 + b / 4;
a = a % 3 + n;
b = b % 4 + n;
ans += n;
}
printf("%d\n", ans);
}
return 0;
}