#include <cstdio>
#include <cmath>
int c;
long double a,b;
int main(){
	while(scanf("%lf %lf %d",&a,&b,&c)!=EOF){
		int ans=0;
		for(int i=10;i<=pow(10.0,c);i*=10){
			int ryu=a/b*i;
			ans+=ryu%10;
		}
		printf("%d\n",ans);
	}
}