{
    int m,t,s,d,h;
    scanf("%d %d %d",&m,&t,&s);
    d=s/t;
    if(t=0){printf("%d",m);return 0;
    }
      else if(s%t==0){d=s/t;}
     else {d=s/t+1;}


    h=m-d;
       if(h>0)
    {printf("%d",h);}
    else  {printf("0");}

    return 0;
}