#include <stdio.h>

#define wielkosc 102

int stringlength(const char *str)
{
    for (int i = 0; ; i++)
    {
        if (str[i] == '\0')
        {
            return i;
        }
    }
}

int main()
{
    char str[wielkosc] = { '\0' };

    printf("Podaj wyrazenie : ");
    fgets(str, wielkosc, stdin);

    str[stringlength(str) - 1] = '\0';

    for (int i = 0; i < wielkosc - 2; ++i)
    {
        if (str[i] == '\0')
            break;

        if (!((str[i] >= '0' && str[i] <= '9') || str[i] == '+' || str[i] == '-'))
        {
            printf("Incorrect input");
            return 1;
        }
    }

    int currentValue = 0;
    char *c = &str[0];
    sscanf(c, "%d", &currentValue);

    {
        char kalkulator[1024];
        sprintf(kalkulator, "%d", currentValue);
        c += stringlength(kalkulator);
    }

    while (*c != '\0')
    {
        char znak;
        int wartosc;

        if (sscanf(c, "%c%d", &znak, &wartosc) == 2)
        {
            if (znak == '+')
            {
                currentValue += wartosc;
            }
            else if (znak == '-')
            {
                currentValue -= wartosc;
            }
        }

        char kalkulator[1024];
        sprintf(kalkulator, "%c%d", znak, wartosc);
        c += stringlength(kalkulator);
    }

    printf("%d", currentValue);
    return 0;
}