#include <stdio.h>
#include <math.h>

int main(void) {
    const double pi = 3.14159;
    double L = 0;
    double C = 0;
    double T = 0;

    printf("Введите L и C: ");
    scanf("%lf %lf", &L, &C);

    T = 2 * pi * sqrt((L*C));
    printf("\n%lf\n", T);
    return 0;
}