#include <bits/stdc++.h>
int main() {
  unsigned int x[3], i, t, n = 0;
  for (i = 0; i < 3; i++) scanf("%u", &x[i]);
  if (x[2] < x[1]) {
    t = x[1];
    x[1] = x[2];
    x[2] = t;
  }
  if (x[2] < x[0]) {
    t = x[0];
    x[0] = x[2];
    x[2] = t;
  }
  while (!(x[0] + x[1] > x[2])) {
    x[2]--;
    n++;
  }
  printf("%u", n);
  return 0;
}
