# import pypyjit
# pypyjit.set_param('max_unroll_recursion=-1')
from collections import *
from itertools import *
from functools import *
import math,sys
input = sys.stdin.readline


B = list(map(int,input().split()))
R = B[1]-B[2]
D = B[0]*B[2] - B[1]**2
x = R*B[2]+D
print(x//(B[0]-B[1]))