#include <stdio.h>
#include <ctype.h>
#include <assert.h>
#include <math.h>

int getint(int *p);
int getfloat(float *p);

/* ungetchar: push char c back to input stream */
#define ungetchar(c) ungetc(c, stdin)


/* tests getfloat, prints input to output, puts valid numbers
 * in brackets : n -> [n] */
int main()
{
    float x;
    int r;
    while ((r = getfloat(&x)) != EOF)
        if (!r) {
            int c;
            putchar(getchar());
            while (!isdigit(c = getchar()) && c != EOF && c != '-' && c != '+')
                putchar(c);
            ungetchar(c);
        } else
            printf("[%g]", x);
    return 0;
}

/* we assert that EOF is negative */
static_assert(EOF < 0, "EOF is not a negative number");

/* ugetint: gets unsigned int from input to n
 * n must be intialized by caller
 * takes optional arguments for loop increment
 * last char read is stored in varvar_c */
#define ugetint(var_c, n, ...) \
    do { \
    for (; isdigit(var_c = getchar()); __VA_ARGS__) \
        n = 10 * (n) + var_c - '0'; \
    } while (0)

/* getint : gets int from input and overwrites it to p
 * returns 1 on valid integer, 0 if no integer is found
 * and EOF on EOF. */
int getint(int *p)
{
    int c;
    if ((c = getchar()) == EOF)
        return EOF;

    /* handle sign */
    int sign = (c == '-') ? -1 : ((c == '+') ? 1 : 0);
    if (sign)
        c = getchar();
    if (!isdigit(c)) { /* not a number */
        ungetchar(c);
        if (sign)
            ungetchar((sign > 0) ? '+' : '-');
        return 0;
    }

    *p = c - '0';
    ugetint(c, *p);
    ungetchar(c);
    *p *= (sign) ? sign : 1;
    return 1;
}

#define DEC_SEP X('.') X(',')
#define EXP_SEP X('e') X('E')

/* getfloat : gets float from input and overwrites it to p
 * returns 1 on valid integer, 0 if no integer is found
 * and EOF on EOF. */
int getfloat(float *p)
{
    char flag;
    int n;
    if ((flag = getint(&n)) < 1) /* not a number */
        return flag;
    *p = n;

    int exp, c = getchar();
    /* fractional part */
#define X(C) c == C ||
    if (DEC_SEP 0) {
        n = exp = 0;
        ugetint(c, n, exp--);
        *p += n * pow(10, exp);
    }
#undef X
    /* exponent part */
#define X(C) c == C || 
    if ((EXP_SEP 0) && getint(&exp)) {
        *p *= pow(10, exp);
    } else
        ungetchar(c);
    return 1;
}