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 Main {
        public static long mod= (long) (1e9 +7);
        public static void main(String args[]){
            InputReader s= new InputReader(System.in);
            OutputStream outputStream= System.out;
            PrintWriter out= new PrintWriter(outputStream);
            int a= s.nextInt();
            int b= s.nextInt();
            int c= s.nextInt();
            int temp= a*c;
            int temp1= (int) Math.ceil((float)temp/(float)b);
            //out.println(temp1);
            int ans= temp1- c;
            out.println(ans);
            out.close();
        }
        static class InputReader {
    
            public BufferedReader reader;
            public StringTokenizer tokenizer;
     
            public InputReader(InputStream inputstream) {
              reader = new BufferedReader(new InputStreamReader(inputstream));
              tokenizer = null;
            }
            
            public String nextLine(){
                String fullLine=null;
                while (tokenizer == null || !tokenizer.hasMoreTokens()) {
                    try {
                      fullLine=reader.readLine();
                    } catch (IOException e) {
                      throw new RuntimeException(e);
                    }
                    return fullLine;
                  }
                  return fullLine;
            }
            public String next() {
              while (tokenizer == null || !tokenizer.hasMoreTokens()) {
                try {
                  tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                  throw new RuntimeException(e);
                }
              }
              return tokenizer.nextToken();
            }
            public long nextLong() {
                  return Long.parseLong(next());
                }
            public int nextInt() {
              return Integer.parseInt(next());
            }
          }
        public static int gcd(int number1, int number2) {  
            if(number2 == 0){
                return number1;
            } 
            return gcd(number2, number1%number2); 
        }
        public static int combinations(int n,int r){
            if(n==r) return 1;
            if(r==1) return n;
            if(r==0) return 1;
            return combinations(n-1,r)+ combinations(n-1,r-1);
        }
    
        public static int expo(int a, int b){
            if (b==1)
                return a;
            if (b==2)
                return a*a;
    
            if (b%2==0){
                    return expo(expo(a,b/2),2);
            }
            else{
                return a*expo(expo(a,(b-1)/2),2);
            }
        }
        
        public static void sieve(int N){
            int arr[]= new int[N+1];
            for(int i=2;i<Math.sqrt(N);i++){
                if(arr[i]==0){
                    for(int j= i*i;j<= N;j= j+i){
                        arr[j]=1;
                    }
                }
            }
            // All the i for which arr[i]==0 are prime numbers.
        }
    }
    
