DCZPROST - wrong answer

Is it possible to somehow see what tests exactly my code does not pass? I am pretty sure my solution is correct and when I check it on my own, the results are correct in all cases. How can I check what fails?

#include <stdio.h>
#include <stdbool.h>

int min(int a, int b) {
    return (a < b) ? a : b;
}

int max(int a, int b) {
    return (a > b) ? a : b;
}

int count_red_squares(int xld, int yld, int xpg, int ypg) {
    int red_count = 0;
    
    for (int y = yld; y < ypg; y++) {
        if (y % 2 == 1) {
            int max_x = min(y, xpg - 1);
            if (max_x >= xld) {
                red_count += max_x - xld + 1;
            }
        }
        
        int start_x = max(y + 1, xld);
        if (start_x < xpg) {
            start_x += (start_x % 2 == 0);
            
            if (start_x < xpg) {
                int count_odds = (xpg - start_x + 1) / 2;
                red_count += count_odds;
            }
        }
    }
    
    return red_count;
}


bool check_input_validity(int xld, int yld, int xpg, int ypg) {
    if (xld < 0 || yld < 0 || xpg < 0 || ypg < 0) {
        printf("xld, yld, xpg and ypg should be positive integers\n");
        return false;
    }
    if (xld > xpg || yld > ypg) {
        printf("xld and yld should be less than xpg and ypg\n");
        return false;
    }
    if (xld > 1000000 || yld > 1000000 || xpg > 1000000 || ypg > 1000000) {
        printf("xld, yld, xpg and ypg should be less than 1000000\n");
        return false;
    }
    return true;
}

int main() {
    int xld, yld, xpg, ypg;
    bool is_input_valid = false;
    
    while (!is_input_valid) {
        scanf("%d %d %d %d", &xld, &yld, &xpg, &ypg);
        is_input_valid = check_input_validity(xld, yld, xpg, ypg);
    }
    
    printf("%d", count_red_squares(xld, yld, xpg, ypg));
    
    return 0;
}