#include <iostream>
using namespace std;
int main() {
int a, b, c;
cin >> a >> b >> c;
if (a > b && a > c){ // daca a va fi cel mai mare
if (b > c) {
cout << (a - c -2);
}
if (c > b) {
cout << (a - b - 2);
}
}
if (b > a && b > c){//daca b va fi cel mai mare
if (a > c) {
cout << (b - c -2);
}
if (c > a) {
cout << (b - a - 2);
}
}
if (c > b && c > a){//daca c va fi cel mai mare
if (b > a) {
cout << (c - a - 2);
}
if (a > b) {
cout << (c - b - 2);
}
}
return 0;
}
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