#include <stdio.h>
#include <stdlib.h>
#include <string.h>

int main()
{
    char *s = "123";

    // int n = atoi(s);

    int n;
    sscanf(s, "%d", &n);

    char buf[100];
    sprintf(buf, "%d\n", n * 2);

    //  sprintf(buf,       "%s\n", p); // unsafe
    // snprintf(buf, size, "%s\n", p); // safe - see man page for detail

    printf("%lu\n", strlen(buf));
    printf("%s", buf);
}