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