993 992 991
 100 1 10
 960 935 994
 99 8 99
 60 16 1
 759 10 258
 24 19 9
 196 169 144
 1000 999 1
 945 812 917
 1000 100 10
 500 300 300
 888 777 1000
 2 1 4
 24 12 12
 767 2 514
 2 1 2
 1000 1 1
 5 2 1
 70 32 1
 765 123 899
 17 7 10
 5 4 10
 888 777 888
 66 38 4
 1000 999 1000
 9 3 300
 244 87 4
 765 123 45
 1000 1 1000
 305 203 421
 100 10 1
 64 12 8
 894 1 999
 2 1 1
 18 14 10
 6 2 4
 888 777 1
 27 26 1
 2 1 3
 5 1 5
 7 3 200
 561 31 917
 17 10 7
 93 74 831

1
 990
 27
 1127
 3
 19325
 3
 24
 1
 151
 90
 200
 143
 4
 12
 196605
 2
 999
 2
 2
 4693
 15
 3
 127
 3
 2
 600
 8
 235
 999000
 212
 9
 35
 892107
 1
 3
 8
 1
 1
 3
 20
 267
 15678
 5
 214

import java.awt.*;
import java.awt.event.*;
import java.awt.geom.*;
import java.io.*;
import java.math.*;
import java.text.*;
import java.util.*;

public class Main {
	static BufferedReader br;
	static StringTokenizer st;
	static PrintWriter pw;

	public static void main(String[] args) throws IOException	{
		br = new BufferedReader(new InputStreamReader(System.in));
		pw = new PrintWriter(new BufferedWriter(new OutputStreamWriter(System.out)));
		long a = readInt();
		long b = readInt();
		long c = readInt();
		long min = 0;
		long max = (long)1e12;
		outer: while(min != max)	{
			long mid = (min+max)/2;
			long load = b * mid;
			for(int sec = 1; sec <= c; sec++)	{
				load += b;
				long num = load / a;
				if(num < sec)	{
					min = mid+1;
					continue outer;
				}
			}
			max = mid;
		}
		pw.println(min);
		pw.close();
	}
	
	public static long readLong() throws IOException	{
		return Long.parseLong(nextToken());
	}
	public static double readDouble() throws IOException	{
		return Double.parseDouble(nextToken());
	}
	public static int readInt() throws IOException	{
		return Integer.parseInt(nextToken());
	}
	public static short readShort() throws IOException	{
		return Short.parseShort(nextToken());
	}
	public static String nextToken() throws IOException	{
		while(st == null || !st.hasMoreTokens())	{
			if(!br.ready())	{
				pw.close();
				System.exit(0);
			}
			st = new StringTokenizer(br.readLine());
		}
		return st.nextToken();
	}
}