#define _CRT_SECURE_NO_WARNINGS 1

#include <stdio.h>
#include <math.h>
int main()
{
    int a, b, c;
    scanf("%d %d %d", &a, &b, &c);
    float p = (float)(a + b + c) / 2;
    float s = sqrt(p * (p - a) * (p - b) * (p - c));
    printf("circumference=%.2f area=%.2f", 2 * p, s);
    return 0;
}


#include <stdio.h>
int main()
{
    int n, h, m;
    scanf("%d %d %d", &n, &h, &m);
    if (m % h > 0)
        printf("%d", n - (m / h) - 1);
    else
        printf("%d", n - (m / h));
    return 0;
}

#include <stdio.h>
int main()
{
    double f = 0.0;
    scanf("%lf", &f);
    printf("%.3lf", (double)5 / 9 * (f - 32));
    return 0;
}


#include <stdio.h>
int main()
{
    int r = 0;
    scanf("%d", &r);
    printf("%.2f", (float)3.14 * r * r);
    return 0;
}



#include <stdio.h>
int main()
{
    int r1 = 0, r2 = 0;
    scanf("%d %d", &r1, &r2);
    printf("%.1f", (float)r1 * r2 / (r1 + r2));
    return 0;
}