# Enter your code here. Read input from STDIN. Print output to STDOUT
import sys
stats = sys.stdin.readline().strip()
stats = stats.split(" ")

# ['a', 'b', 't']

print int( 0.5 * int(stats[0]) * int(stats[2]) + 0.5 * int(stats[1]) * int(stats[2]) ) % (10**9 + 7)