#include <stdio.h>
#include <math.h>
int main() {
double a, b, c, d, x, max, min;
fflush(stdout
); // Принудительно выводим приглашение
scanf("%lf %lf %lf %lf", &a
, &b
, &c
, &d
);
// Находим максимум
max = a;
if (b > max) max = b;
if (c > max) max = c;
if (d > max) max = d;
// Находим минимум
min = a + c;
if ((b - d) < min) min = b - d;
// Вычисляем результат
x = max + min;
return 0;
}
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