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.lang.*;
import java.math.*;
import java.text.DecimalFormat;
import java.text.NumberFormat;
import java.io.*;
public class Solution {
	static class FastReader {
        BufferedReader br;
        StringTokenizer st;

        public FastReader() {
            br = new BufferedReader(new
                    InputStreamReader(System.in));
        }
        String next() {
            while (st == null || !st.hasMoreElements()) {
                try{
                    st = new StringTokenizer(br.readLine());
                }
                catch (IOException  e) {
                    e.printStackTrace();
                }
            }
            return st.nextToken();
        }
        int nextInt() {
            return Integer.parseInt(next());
        }
        long nextLong() {
            return Long.parseLong(next());
        }
        static int fact(int n) {
   		 if(n == 1) {
   			 return 1;
   		 }
   		 return n * fact(n-1);
   	 }
	public int[] readIntArray(int n) {
			int[] arr = new int[n];
			for(int i=0; i<n; ++i)
				arr[i]=nextInt();
			return arr;
		}

        double nextDouble() {
            return Double.parseDouble(next());
        }

        String nextLine() {
            String str = "";
            try{
                str = br.readLine();
            }
            catch (IOException e) {
                e.printStackTrace();
            }
            return str;
        }
    }
	 static int solve(int a, int b, int c) {
		 int count = 0;
		 int total = 0;
		
		 while(c > 0) {
			 if(total + b < a) {
				 count++;
			 }
			 else {
				 total = total + b - a;
				 c--;
				 continue;
			 }
			 total += b;
		 }
		 return count;
	 }
	public static void main(String args[]) {
        FastReader sc = new FastReader();
        long start = System.currentTimeMillis();
        int a = sc.nextInt(), b = sc.nextInt(), c = sc.nextInt();
       
        	System.out.println(solve(a,b,c));
        	long end = System.currentTimeMillis();
        	NumberFormat formatter = new DecimalFormat("#0.00000");
        	//System.out.print("Execution time is " + formatter.format((end - start) / 1000d) + " seconds");
        }
}
