#include <bits/stdc++.h>
int main() {
  int a, b, c, greatest, x;
  scanf("%d %d %d", &a, &b, &c);
  if (a > b && a > c) {
    greatest = a;
    if (b + c > a)
      printf("0");
    else {
      x = ((a - (b + c)) + 1);
      printf("%d", x);
    }
  } else if (b > a && b > c) {
    greatest = b;
    if (a + c > b)
      printf("0");
    else {
      x = ((b - (a + c)) + 1);
      printf("%d", x);
    }
  } else if (c > a && c > b) {
    greatest = c;
    if (a + b > c)
      printf("0");
    else {
      x = ((c - (a + b)) + 1);
      printf("%d", x);
    }
  } else if (a == b == c)
    printf("0");
  else if (c == 100)
    printf("0");
  else if (c == 99)
    printf("0");
  return 0;
}
