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Problems

Cost of call

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 (0a, b99, 0n86400).

Output

Print the cost of a phone call in kopecks.

Time limit 1 second
Memory limit 128 MiB
Input example #1
5 10 120
Output example #1
25