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

void Usage(void){
	printf("Usage:\n");
	printf("\t./stock [commission] [in] [out] [shares]\n");
	printf("\t\tcommission: roundtrip\n");
}


int main(int argc, char **argv){
	if(argc != 5){
		Usage();
		exit(1);
	}

	//int num1;
	double com, in, out, shares, tmp1, tmp2, diff;

	com = atof(argv[1]);
	in = atof(argv[2]);
	out = atof(argv[3]);
	shares = atof(argv[4]);

	tmp1 = shares*in;
	tmp2 = shares*out;
	diff = (tmp1*-1)+tmp2;

	printf("profit/loss: %lf\n", diff-com);

	return 0;
}