// yukicoder: No.810 割った余りの個数
// 2019.4.13 bal4u

#include <stdio.h>

#if 1
#define gc() getchar_unlocked()
#else
#define gc() getchar()
#endif

int in()    // 非負整数の入力
{
	int n = 0, c = gc();
	do n = 10 * n + (c & 0xf), c = gc(); while (c >= '0');
	return n;
}

int main()
{
	int L, R, M, ans;

	L = in(), R = in(), M = in();
	ans = R - L + 1;
	if (ans >= M) ans = M;
	printf("%d\n", ans);
	return 0;
}