#include <stdio.h>
double calculate_sum(int n) {
    double sum = 0.0;
    for (int k = 1; k <= n; k++) {
        sum += 1.0 / (k * (k + 1)); // セミコロンを付けて修正
    }
    return sum;
}

int main(void) {
    int n1 = 3;
    int n2 = 10;
    double result_n1 = calculate_sum(n1);
    double result_n2 = calculate_sum(n2);

    printf("x(%d) = %f\n", n1, result_n1);
    printf("x(%d) = %f\n", n2, result_n2);
  
return 0;
}