#include <stdio.h>

int main() {
    int a,b,c,d,e,m;
    scanf("%d%d%d",&a,&b,&c);//a=n,b=h,c=m//m=a-b*c;
    e=c%b;
    if(e==0)
    d=c/b;
    else
    d=c/b+1;//没喝完要加1
    m=a-d;
    printf("%d\n",m);
    return 0;
}