#include <stdio.h>

double maxelem(FILE* f);

int main() {
    FILE* f = fopen("input.txt", "r");
    if (f == NULL) {
        perror("Cannot open a file");
        return (-1);
    }
    
    double y = maxelem(f);    
    fclose(f);
    
    printf("Maximal element: %g\n", y);
    return 0;
}

double maxelem(FILE* f) {
    double y = -1e30;  // -infinity
    double x;
    while (fscanf(f, "%lf", &x) == 1) {
        if (x > y)
           y = x;
    }
    return y;
}