#include <stdio.h>
#include <math.h>
 
struct Triangle {
    double a;
    double b;
    double c;
};
 
int main(void)
{
    struct Triangle t;
    double p; 
    double s;  
 
    scanf("%lf", &t.a);
    scanf("%lf", &t.b);
    scanf("%lf", &t.c);
 
 
    p = (t.a + t.b + t.c) / 2.0;
    s = sqrt(p * (p - t.a) * (p - t.b) * (p - t.c));
 
 
    printf("a: %.0lf\n", t.a);
    printf("b: %.0lf\n", t.b);
    printf("c: %.0lf\n", t.c);
    printf("三角形の面積: %f\n", s);
 
    return 0;
}
 

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