I need help :((

Here is the problems’s prompt :
computer displays the folder under multiple rows, each containing up to m folders. Assuming drive has n directories, the folders are numbered 1 through n and are ordered from left to right and from top to bottom . I wants to copy all the folders with word numbers a to b to another drive. However, i doesn’t know that i just holds down Shift then click to select folders a and b then continue to perform copy operations, how i done is hold down the Ctrl key and drag the mouse pointer to select a group of folders by frame rectangle (with sides parallel to the screen). If the folder selection is repeated (select a folder has been selected) then the folder will no longer be selected.

  • Input: Single line contains n,m,a,b (1 <= n,m <= 10^9, 1 <= a,b <= n) is the number of folders on my computer, the maximum number of folders per row horizontal, the number of the first and last directory that i want to copy.
  • Output: Print out the least number of mouse drag to select the frame that i must perform is displayed when you want to select all folders from a to b.

Here is my code but it got the wrong answer

#include <stdio.h>

int main(){
    unsigned int n,m,a,b;
    scanf("%u %u %u %u",&n,&m,&a,&b);

    unsigned int positionA, positionB;

    unsigned int rowA,rowB;

    // Position of B and row of B
    if(b % m == 0){
        //b at the end of a row
        positionB = m;
        rowB = (b/m)-1;
        positionB = b % m;
        rowB = b/m;

    //Position of A and row of A
    if(a % m == 0){
        //a at the end of a row
        positionA = m;
        rowA = (a/m)-1;
        positionA = a % m;
        rowA = a/m;

    //Start checking
    if(rowA == rowB) printf("%d",1);
    else if(rowB - rowA == 1){
        if(positionA == 1 && positionB == m) printf("%d",1);
        else printf("%d",2);
    else {
        if(positionA == 1 && positionB == m) printf("%d",1);
        else if(positionA != 1 && positionB != m) printf("%d",3);
        else printf("%d",2);

    return 0;