#include<stdio.h>
#include<math.h>
int main()
{
    float a,b,c,s,r;

    printf("length of side a");
    scanf("%f", &a);

    printf("lenght of side b");
    scanf("%f", &b);

    printf("lenght of side c");
    scanf("%f", &c);

    s=(a+b+c)/2;

    printf("semiperimeter of traingle is s %f",s);

    r=sqrt(s*(s-a)*(s-b)*(s-c));

    printf("area of traingle is r %f",r);

    return 0;
}