#include <stdio.h>
#include <sys/stat.h>
#include <unistd.h>
#include <sys/mman.h>
#include <fcntl.h>

int main(int argc, char* argv[]) {
    double sum = 0;
    int fd = open(argv[1], O_RDONLY);
    struct stat buf;
    fstat(fd, &buf);
    double *map = mmap(0, buf.st_size, PROT_READ, MAP_SHARED, fd, 0);
    size_t size = buf.st_size / sizeof(double);
    for (size_t i = 0; i < size; i++) {
        sum += map[i];
    }
    printf("%a\n", sum / size);
    munmap(0, buf.st_size);
    close(fd);
}