//余数化一法
#include <stdio.h>
int main()
{
    int n, h, m;
    scanf("%d%d%d", &n, &h, &m);
    printf("%d\n", n - m / h - (m % h + 2) % (m % h + 1));
    //余数化一法: (m % h + 2) % (m % h + 1)
    return 0;
}