import sys, time, random
from collections import deque, Counter, defaultdict
input = lambda: sys.stdin.readline().rstrip()
ii = lambda: int(input())
mi = lambda: map(int, input().split())
li = lambda: list(mi())
inf = 2 ** 63 - 1
mod = 998244353

w, z, b = input().split()
w = int(w)
z = int(z)
b = float(b)

print(round((w + z) * (1 + b)))