#include <stdio.h>

int main() {
    float Sum, i, n, Numerator;
    Sum = 0;
    printf("Subject: Calculate the amount \n");
    printf("Enter the 'n' number: \n");
    scanf_s("%f", & n);
    while (n < 1) {
        printf("Enter positive number \n");
        scanf_s("%f", & n);
    }
    for (int i = 1; i <= n; i++) {
        if (i % 2 == 0) {
            Numerator = 1;
        } else {
            Numerator = -1;
        }
        Sum = Sum + (Numerator / (2 * i));
    }
    printf("The amount is: %.3f \n", Sum);
    getch();
}