https://www.acmicpc.net/problem/2869
using System;
class Program
{
static void Main() {
string[] s=Console.ReadLine().Split(' ');
int a=int.Parse(s[0]);
int b=int.Parse(s[1]);
int v=int.Parse(s[2]);
int k=(v-b)/(a-b);
int m=(v-b)%(a-b);
if(m==0) Console.Write("{0}",k);
else Console.Write("{0}",k+1);
}
}