#include <stdio.h>
#include <stdlib.h>

int main() {
	int a, b, s;
	scanf("%d %d %d", &a, &b, &s);

	int da = abs(s - a), db = abs(s - b);
	int ans;

	if (da <= db) ans = da + s;
	else ans = da + db + (s - 1) * 2 + 1;

	printf("%d\n", ans);
	return 0;
}