#include <bits/stdc++.h>
#define rep(i,n) for(int i = 0; i < (n); i++)
using namespace std;
typedef long long ll;

int main(){
    cin.tie(0);
    ios::sync_with_stdio(0);
    
    // b2 = r b1 + d
    // b3 = r b2 + d
    // r = (b3 - b2) / (b2 - b1)
    // x = r b3 + d = r b3 + (b2 - r b1)

    ll b[4]; rep(i,3) cin >> b[i+1];
    ll ru = b[3] - b[2];
    ll rl = b[2] - b[1];
    ru *= b[3] - b[1];
    ru += rl * b[2];
    ll g = gcd(ru, rl);
    cout << ru / g * (rl < 0 ? -1 : +1) << endl;
}