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.util.*;
import java.io.*;

public class Solution {

	static Scanner scn = new Scanner(System.in);
	static StringBuilder sb = new StringBuilder();

	public static void main(String[] HastaLaVistaLa) {
		int t = 1;
		while(t-- > 0) solve();
		System.out.println(sb);
	}

	public static void solve() {
		// Insert an inspiration Quote here
		int a = scn.nextInt(), b = scn.nextInt(), c = scn.nextInt();
		int toDown = a * c, took = (toDown + b - 1) / b;
		int canGet = (b * c);
		int left = toDown - canGet, min = 1, max = took;
		while(min < max) {
			int mid = min + (max - min) / 2;
			if(mid * b >= left) max = mid;
			else min = mid + 1;
		}
		sb.append(min);
	}
}