#include <bits/stdc++.h>
int main() {
  int a, b, c, t, i = 0;
  scanf("%d%d%d", &a, &b, &c);
  if (a > b) {
    t = a;
    a = b;
    b = t;
  }
  if (a > c) {
    t = a;
    a = c;
    c = t;
  }
  if (b > c) {
    t = b;
    b = c;
    c = t;
  }
  while (c - a >= b) {
    a++;
    i++;
  }
  printf("%d", i);
  return 0;
}
