def read_data():
    A, B, T = map(int, input().split())
    return A, B, T

def approximate(A, B, T):
    result = float('inf')
    for b in range(A):
        # b * B + a * A >= r
        a = max(0, ((T - b * B - 1) // A) + 1)
        ab = a * A + b * B
        if ab < result:
            result = ab
        if ab == T:
            return T
    return result
    
if __name__ == '__main__':
    A, B, T = read_data()
    print(approximate(A, B, T))