#include <bits/stdc++.h>
int main() {
  int a, b, c, x, y, z, t;
  scanf("%d %d %d", &a, &b, &c);
  if (a >= b && a >= c) {
    z = a;
    y = b;
    x = c;
  } else if (b >= a && b >= c) {
    z = b;
    y = a;
    x = c;
  } else {
    z = c;
    y = a;
    x = b;
  }
  if (z < x + y)
    printf("0");
  else {
    t = z - x - y + 1;
    printf("%d", t);
  }
  return 0;
}
