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

#Author : Zahin uddin
#Github : https://github.com/Zahin52


from sys import *
#import math
#import queue
input=stdin.readline
listInput=lambda:list(map(int,input().strip().split()))
lineInput= lambda:map(int,input().strip().split())
sJoin=lambda a,sep : f'{sep}'.join(a)
arrJoin=lambda a,sep : f'{sep}'.join(map(str,a))
#print=stdout.write
def isPrime(n):
    if(n <= 1):
        return False
    if(n <= 3):
        return True
    if(n % 2 == 0 or n % 3 == 0):
        return False
    for i in range(5,int(math.sqrt(n) + 1), 6):
        if(n % i == 0 or n % (i + 2) == 0):
            return False
    return True
def binarySearch(low,high,a,b,c,data):
    while low<=high:        
        mid=(low+high)//2    
        oneSecEarly=((mid*b)+(b*(c-1))) 
        #print(mid,oneSecEarly,data-oneSecEarly)   
        if 0<data-oneSecEarly<=b:
            return mid
            break
        elif data-oneSecEarly<=0:
            high=mid-1
        elif data-oneSecEarly>b:
            low=mid+1
def main():
    a,b,c=lineInput()
    downloadtime=((a*c)+b-1)//b
    #print(downloadtime)
    ans=binarySearch(0,downloadtime,a,b,c,(a*c))
    print(ans)
    
    
if __name__ == "__main__":
    main()
