#define _USE_MATH_DEFINES
#include <bits/stdc++.h>
using namespace std;
const long long INF = LLONG_MAX;
signed main() { 
  ios::sync_with_stdio(false); cin.tie(0);
  auto is_valid = [] (long long g[], long long h[]) -> bool {
    // if (h[0] < g[0] || h[1] < g[1] || h[2] < g[2]) return false;
    // if (g[0] <= 0 || g[1] <= 0 || g[2] <= 0) return false;
    if (g[0] == g[1] || g[1] == g[2] || g[2] == g[0]) return false;
    if (g[1] > g[0] && g[1] > g[2]) return true;
    if (g[1] < g[0] && g[1] < g[2]) return true;
    return false;
  };
  auto solve = [&] () -> long long {
    long long h[3];
    cin >> h[0] >> h[1] >> h[2];
    long long c[3];
    // cin >> c[0] >> c[1] >> c[2];
    c[0] = c[1] = c[2] = 1;
    long long t[] = {h[0], h[0] - 1, h[0] - 2, h[1], h[1] - 1, h[1] - 2, h[2], h[2] - 1, h[2] - 2};
    long long g[3];
    long long res = INF;
    for (int i = 0; i < 9; i++) for (int j = 0; j < 9; j++) for (int k = 0; k < 9; k++) {
      g[0] = t[i], g[1] = t[j], g[2] = t[k];
      if (h[0] < g[0] || h[1] < g[1] || h[2] < g[2]) continue;
      if (g[0] <= 0 || g[1] <= 0 || g[2] <= 0) continue;
      if (!is_valid(g, h)) res = min(res,  c[0] * (h[0] - g[0]) + c[1] * (h[1] - g[1]) + c[2] * (h[2] - g[2]));
    }
    return (res == INF ? -1 : res);
  };
  cout << solve () << '\n';
  return 0;
  int t;
  cin >> t;
  while (t--) cout << solve() << '\n';
  return 0;
}