Find the cost of a phone call in kopecks with duration of $n$ seconds, if the connecting cost is $a$ kop., the tariffication is per minute, that is the first second of each minute is charged to pay $b$ kop. \InputFile Three non-negative integers $a, b$ and $n~(0 \le a, b \le 99, 0 \le n \le 86400)$. \OutputFile Print the cost of a phone call in kopecks.