#include <bits/stdc++.h>
#define ll long long
#define INF 1000000005
#define MOD 1000000007
#define EPS 1e-10
#define rep(i,n) for(int i=0;i<(int)n;++i)
#define each(a, b) for(auto (a): (b))
#define all(v) (v).begin(),(v).end()
#define fi first
#define se second
#define pb push_back
#define show(x) cout <<#x<<" = "<<(x)<<endl
#define spair(p) cout <<#p<<": "<<p.fi<<" "<<p.se<<endl
#define svec(v) cout<<#v<<":";rep(kbrni,v.size())cout<<" "<<v[kbrni];cout<<endl
#define sset(s) cout<<#s<<":";each(kbrni,s)cout <<" "<<kbrni;cout<<endl

using namespace std;

typedef pair<int,int>P;

const int MAX_N = 100005;

int main()
{
    double a,b,c;
    cin >> a >> b >> c;
    double r = (c - b) / (b - a);
    double d = c - r*b;
    double hoge = r*c + d;
    int res = (int)(r*c + d);
    if(abs(res - hoge) < 0.1){
        cout << res << endl;
    }else if(abs(res+1 - hoge) < 0.1){
        cout << res + 1 << endl;
    }else{
        cout << res - 1 << endl;
    }
    return 0;
}