With using functions, I'm supposed to find the total mass of a snowman.

For some reason, it's giving me the wrong answer:

Code:

#include <stdio.h>
#define PI 3.14159
#define SNOW_DEN 0.1
double Sphere_Volume( double radius);
double Sphere_Mass (double den, double volume);
int main() {
int radius_1, radius_2, radius_3;
double total_volume;
double total_mass;
printf("What is the radii of the head, body and leg of the snowman?\n");
scanf("%lf%lf%lf", &radius_1, &radius_2, &radius_3);
total_volume= Sphere_Volume(radius_1)+ Sphere_Volume(radius_2) + Sphere_Volume(radius_3);
total_mass= Sphere_Mass(SNOW_DEN, total_volume);
printf("The total Mass in grams is %lf.\n", total_mass);
system("PAUSE");
return 0;
}
double Sphere_Volume( double radius){
return 4*PI/3*radius*radius*radius;
}
double Sphere_Mass (double den, double volume){
return SNOW_DEN*volume;
}

Where am I doing wrong?