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