#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#define MAX_SIZE 30
// Функция для вычисления среднего значения
double calculate_mean(int *data, int size) {
double sum = 0.0;
for (int i = 0; i < size; i++) {
sum += data[i];
}
return sum / size;
}
// Функция для вычисления дисперсии
double calculate_variance(int *data, int size, double mean) {
double variance = 0.0;
for (int i = 0; i < size; i++) {
variance += (data[i] - mean) * (data[i] - mean);
}
return variance / size;
}
// Функция для поиска нужного числа
int search_value(int *data, int size, double mean, double threshold) {
for (int i = 0; i < size; i++) {
if (data[i] % 2 == 0 && data[i] >= mean && data[i] <= threshold && data[i] != 0) {
return data[i];
}
}
return 0; // Если не найдено удовлетворяющее условие число
}
int main() {
int data[MAX_SIZE];
int size = 0;
// Чтение данных из stdin
if (scanf("%d", &size) != 1 || size < 1 || size > MAX_SIZE) {
printf("n/a\n");
return 1; // Некорректный ввод
}
for (int i = 0; i < size; i++) {
if (scanf("%d", &data[i]) != 1) {
printf("n/a\n");
return 1; // Некорректный ввод
}
}
// Вычисление среднего и дисперсии
double mean = calculate_mean(data, size);
double variance = calculate_variance(data, size, mean);
double threshold = mean + 3 * sqrt(variance);
// Поиск значения
int result = search_value(data, size, mean, threshold);
printf("%d\n", result);
return 0;
}
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