#include <iostream>
using namespace std;
int main()
{
int numbers[3] = {};
int swapint = 0,counter = 0;
for (int i = 0; i < 3; i++)
{
cin>>numbers[i];
}
for (int i = 0; i < 3; i++)
{
if(numbers[i] > numbers[i+1])
{
swapint = numbers[i] ;
numbers[i] = numbers[i+1];
numbers[i+1] = swapint;
}
}
while (numbers[0]+numbers[1]<= numbers[2])
{
counter++;
numbers[1]++;
}
cout << counter<< endl;
}
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