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.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
 
public class VideoScratch {
    public static void main(String[] args) throws IOException {
        try (BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
             BufferedWriter writer = new BufferedWriter(new OutputStreamWriter(System.out))) {
            String[] input = reader.readLine().split("\\s");
            
            int a = Integer.parseInt(input[0]);
            int b = Integer.parseInt(input[1]);
            int c = Integer.parseInt(input[2]);
 
            writer.write(String.valueOf(timeToWait(a, b, c)));
        }
    }
 
    static int timeToWait(int a, int b, int c) {
        int bad = 0;
        int good = a * c / b;
 
        while (good - bad > 1) {
            int t = (good + bad) / 2;
            if (isEnough(a, b, c, t)) {
                good = t;
            } else {
                bad = t;
            }
        }
 
        return good;
    }
 
    private static boolean isEnough(int a, int b, int c, int t) {
        return (t + c) * b >= a * c;
    }
}