Cost of call

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.

Input

Three non-negative integers $a,b$ and $n(0\le a,b\le 99,0\le n\le 86400)$.

Output

Print the cost of a phone call in kopecks.

Examples