#include<stdio.h>

int main(int argc, char ** argv){

	char multiply = 0;
	if(argc > 1){
		if(argv[1][0] == '-' && argv[1][1] == 'h'){
			printf("Stream Adder:  Adds up numbers from stdin\nUsage:  %s [-m] [-h]\n", argv[0]);
			return 0;
		}
		else if(argv[1][0] == '-' && argv[1][1] == 'm')
			multiply = 1;
		else {
			printf("Unrecognized Argument:  %s\n", argv[1]);
			return 1;
		}
	}

	float sum = multiply;
	float n;
	while(EOF != scanf("%f", &n)){
		if(multiply)
			sum *= n;
		else
			sum += n;
	}
	printf("%f\n", sum);
	return 0;
}