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