#include"stdio.h"
 #include"math.h"
 int main() 
 {
 int m,t,s;
 scanf("%d%d%d",&m,&t,&s);
 if(t<=0||m<=0||s<=0) printf("0");
 if((int)(s*1.0/t+0.999)<m)
 printf("%d",m-(int)(s*1.0/t+0.99999));
 else
 printf("0");
 return 0;
 }