#include<stdio.h>
#include<math.h>
#include<limits.h>

float checkGia(float min, float max){
	float num;
	int check;
	char c;
	do{
		check = scanf("%f%c", &num, &c);
        if(check!=2|| c!='\n'||num<min||num>max){
        	printf("Please enter again!\n\t Enter a positive number smaller than 500: ");
        	fflush(stdin);
        	check = 0;
		}else{
			if(check ==1);
		}
	}while(check==0);
	return num;	
}

int checkKhach(int min, int max){
	int num;
	int check;
	char c;
	do{
		check = scanf("%d%c", &num, &c);
        if(check!=2|| c!='\n'||num<min||num>max){
        	printf("Please enter again!\n\t Enter a positive number smaller than 10000: ");
        	fflush(stdin);
        	check = 0;
		}else{
			if(check ==1);
		}
	}while(check==0);
	return num;	
}

int main(){
	int hopT=200, hopB=50;
	float giaT, giaB, gia;
	int n, soT=0, soB=0;
	
	printf("What is the cost of a small package (in dollars)?\n");
	giaB = checkGia(0.0,500.0);
	
	printf("What is the cost of a big package (in dollars)?\n");
	giaT = checkGia(0.0,500.0);
	
	printf("How many invitation are yeu sending out?\n");
	n = checkKhach(0,10000);
	
	if(4*giaB<giaT){
		soB = ceil(n/50);
	}else{
		soT = n/200;
		int du = n%200;
		if(ceil(du/50)*giaB < giaT){
			soB = ceil(du/50);
		}else{
			soT = soT +1;
		}
	}
	
	gia = soT*giaT + soB*giaB;
	
	printf("\nYou should order %d small package(s).", soB);
	printf("\nYou should order %d big package(s).", soT);
	printf("\nYour cost for invitation will be $%f.", gia);
	return 0;
}