import java.io.IOException;

public class Main {

	public static void main(String[] args) {
		int A = nextInt();
		int B = nextInt();
		int T = nextInt();
		long min = Long.MAX_VALUE;

		for (int i = 0;; i++) {
			int j = (T - B * i + A - 1) / A;
			long next = B * i + A * j;

			min = Math.min(min, next);
			if (B * i > T || i > A) {
				break;
			}
		}

		System.out.println(min);

	}

	static int nextInt() {
		int c;
		try {
			c = System.in.read();
			while (c != '-' && (c < '0' || c > '9'))
				c = System.in.read();
			if (c == '-')
				return -nextInt();
			int res = 0;
			while (c >= '0' && c <= '9') {
				res = res * 10 + c - '0';
				c = System.in.read();
			}
			return res;
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		return -1;
	}
}