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