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.Point;
import java.io.*;
import java.lang.reflect.Array;
import java.math.BigInteger;
import java.util.*;

import static java.lang.Math.*;
     
public class Solution implements Runnable {
 
        BufferedReader in;
        PrintWriter out;
        StringTokenizer tok = new StringTokenizer("");
 
        public static void main(String[] args) {
                new Thread(null, new Solution(), "", 256 * (1L << 20)).start();
        }
 
        public void run() {
                try {
                        long t1 = System.currentTimeMillis();
                        if (System.getProperty("ONLINE_JUDGE") != null) {
                                in = new BufferedReader(new InputStreamReader(System.in));
                                out = new PrintWriter(System.out);
                        } else {
                                in = new BufferedReader(new FileReader("input.txt"));
                                //out = new PrintWriter("output.txt");
                                out = new PrintWriter(System.out);
                        }
                        Locale.setDefault(Locale.US);
                        solve();
                        in.close();
                        out.close();
                        long t2 = System.currentTimeMillis();
                        System.err.println("Time = " + (t2 - t1));
                } catch (Throwable t) {
                        t.printStackTrace(System.err);
                        System.exit(-1);
                }
        }
 
        String readString() throws IOException {
                while (!tok.hasMoreTokens()) {
                        tok = new StringTokenizer(in.readLine());
                }
                return tok.nextToken();
        }
 
        int readInt() throws IOException {
                return Integer.parseInt(readString());
        }
 
        long readLong() throws IOException {
                return Long.parseLong(readString());
        }
 
        double readDouble() throws IOException {
                return Double.parseDouble(readString());
        }
 
        // solution
        
        void solve() throws IOException {
        	int a = readInt(), b = readInt(), c = readInt();       	
        	
        	for(int ans = 0; ;ans++){
        		if((ans + c)*b >= a*c){
        			out.println(ans);
        			return;
        		}
        	}
        }
    }