#include <bits/stdc++.h>
using namespace std;
int main() {
  int a, b, c;
  while (~scanf("%d%d%d", &a, &b, &c)) {
    int a1 = b + c, b1 = a + c, c1 = a + b;
    if (a1 > a && b1 > b && c1 > c)
      printf("0\n");
    else {
      int minn = 9999999;
      minn = minn > (a1 - a) ? (a1 - a) : minn;
      minn = minn > (b1 - b) ? (b1 - b) : minn;
      minn = minn > (c1 - c) ? (c1 - c) : minn;
      printf("%d\n", -minn + 1);
    }
  }
  return 0;
}
