class Tarai {
static public void main(String args[]) {
System.out.println(tarai(20, 10, 5));
}
static private int tarai(int x, int y, int z) {
if (x <= y) {
return y;
} else {
return tarai(tarai(x-1, y, z),
tarai(y-1, z, x),
tarai(z-1, x, y));
}
}
}