#include <stdio.h>
int main() {
// рабочие переменные
int i, n;
double r;
// ввод количества элементов суммы
if( scanf("%d", &n) <= 0 )
{
printf("error: missing n\n" );
return 0;
}
// проверка количества элементов суммы
if( n <= 0 )
{
printf("error: out of range: n=%d\n", n);
return 0;
}
// ввод чисел " а "
for( i = 0, r = 0; i < n; i++ )
{
double a = 0;
if( scanf("%lf", &a ) <= 0 )
{
printf("error: incomplete input of value #%d\n", i);
return 0;
}
// основный цикл вычисления
r += a * a;
}
// вывод результата
printf("result: %lf\n", r );
return 0;
}
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