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.Scanner;

public class main
{
	public static void main(String arg[])
	{

		Scanner in = new Scanner(System.in);
/*
		double a = 14.0;
		double b = 3.0;
		
		double c = a/b;
		

		System.out.println(c);
		System.out.println(Math.ceil(c));
	*/	
		//while (true)
		//{
			int r3;

			int watch = in.nextInt();
			int dl = in.nextInt();
			int length = in.nextInt();

			double r = length * watch;
			double r2 = (r - (length * dl)) / (double) dl;

			if ((r2 - (int) r2) > 0.0)
			{
				r3 = (int) r2 + 1;
			} 
			else
			{
				r3 = (int) r2;
			}
			
			if (r2 >0 && r2 < 1)
				r3 =1;
			//r3 = (int) r2 + 1;
			
			
			System.out.println((int)Math.ceil(r2));
		}
	//}

}
