Some task

//https://www.e-olymp.com/uk/problems/1017

#include <stdio.h>
#define lli long long int

struct num {
    lli sign;
    lli integer;
    lli numerator;
    lli denominator;

    num() {
        sign = 1;
        integer = 0;
        numerator = 0;
        denominator = 1;
    }
};

lli cutNum(lli *pos, char s[]) {
    lli num = 0, fpos = *pos, d = 1;

    while (s[fpos] >= 48 && s[fpos] <= 57) {
        fpos++;
    }
    fpos--;

    for (lli i = fpos; i >= *pos; i--) {
        num += (s[i] - '0') * d;
        d *= 10;
    }

    *pos = fpos+1;

    return num;
}

void readNum(num *n) {
    char s[21];
    lli pos = 0, a = 0, b = 0, c = 0;
    gets(s);

    if (s[0] == '-') {
        pos++;
        (*n).sign = -1;
    }

    a = cutNum(&pos, s);

    if (s[pos] == '/') {
        (*n).numerator = a;
        pos++;

        b = cutNum(&pos, s);
        (*n).denominator = b;

    } else if (s[pos] == ' ') {
        (*n).integer = a;
        pos++;

        if (s[pos] != '\0') {
            b = cutNum(&pos, s);
            pos++;
            c = cutNum(&pos, s);

            (*n).numerator = b;
            (*n).denominator = c;
        }
    } else if (s[pos] == '\0') {
        (*n).integer = a;
    }

}

void printNum(num n) {
    if (n.integer == 0 && n.numerator == 0) printf("0");
    else {
        if (n.sign == -1) printf("-");
        if (n.integer != 0) printf("%lli ", n.integer);
        if (n.numerator != 0) printf("%lli/%lli", n.numerator, n.denominator);
    }

    printf("\n");
}

lli nod(lli a, lli b) {
    if (a == b) {
         return a;
    }
    while (a && b) {
        if (a > b) {
            a %= b;
        } else {
            b %= a;
        }
    }
    return a + b;
}

void simplify(lli *a, lli *b) {
    while (nod(*a, *b) != 1) {
        lli c = nod(*a, *b);
        *a /= c;
        *b /= c;
    }
}

num mult(num a, num b) {
    num c;
    lli m1 = a.integer*a.denominator + a.numerator;
    lli m2 = b.integer*b.denominator + b.numerator;

    lli n = m1*m2;
    lli d = a.denominator * b.denominator;

    simplify(&n, &d);

    c.integer = n/d;
    n -= d*c.integer;
    c.numerator = n;
    c.denominator = d;

    c.sign = a.sign*b.sign;

    return c;
}

num div(num a, num b) {
    lli c = b.numerator;
    b.numerator = b.denominator;
    b.denominator = c;

    return mult(a, b);
}

lli nok(lli a, lli b) {
    return a*b/nod(a, b);
}

num sum(num a, num b) {
    num c;
    lli n, d;

    d = nok(a.denominator, b.denominator);
    n = a.sign*a.integer*d + a.sign*a.numerator*d/a.denominator + b.sign*b.integer*d + b.sign*b.numerator*d/b.denominator;
    if (n < 0) {
        c.sign = -1;
        n *= -1;
    }

    simplify(&n, &d);

    c.integer = n/d;
    n -= d*c.integer;
    c.numerator = n;
    c.denominator = d;

    return c;
}

num dif(num a, num b) {
    b.sign *= -1;
    return sum(a, b);
}

num fn(char s, num a, num b) {
    if (s == '+') return sum(a, b);
    if (s == '-') return dif(a, b);
    if (s == '*') return mult(a, b);
    return div(a, b);
}

num a, b, c;
char f;

int main() {

    readNum(&a);

    scanf("%c\n", &f);

    readNum(&b);

    c = fn(f, a, b);

    printNum(c);

    return 0;
}