A, B, T = map(int, input().split())
import math

min_total = float('inf')

# Consider using only A
num_a = (T + A - 1) // A
min_total = min(min_total, num_a * A)

# Consider using only B
num_b = (T + B - 1) // B
min_total = min(min_total, num_b * B)

# Consider combinations of A and B
max_k = (T + B - 1) // B  # Equivalent to ceil(T / B)
# To handle large values, limit the range if necessary
max_k = min(max_k, 10**7)  # Safeguard against very large k

for k in range(0, max_k + 1):
    remaining = T - k * B
    if remaining <= 0:
        total = k * B
    else:
        m = (remaining + A - 1) // A
        total = k * B + m * A
    if total < min_total:
        min_total = total

print(min_total)