Shadows of the Knight - Episode 1 - Puzzle discussion

Puzzles
94

here is my c++ code ,but it just pass a few test, most of the failed tests is about the late time , i think the range should be revised , but i dont nknow how to develop this code

 #include <iostream>
#include <string>
#include <vector>
#include <algorithm>

using namespace std;

/**
 * Auto-generated code below aims at helping you parse
 * the standard input according to the problem statement.
 **/
int main()
{
    int W; // width of the building.
    int H; // height of the building.
    cin >> W >> H; cin.ignore();
    int N; // maximum number of turns before game over.
    cin >> N; cin.ignore();
    int X0;
    int Y0;
    int first_x =0 ;
    int first_y = 0;
    int last_x = W;
    int last_y = H;
    //the batman start location.
    cin >> X0 >> Y0; cin.ignore();

    // game loop
    while (1) {
        string bombDir; // the direction of the bombs from batman's current location (U, UR, R, DR, D, DL, L or UL)       
        cin >> bombDir; cin.ignore();

        // Write an action using cout. DON'T FORGET THE "<< endl"
        if(bombDir[0] == 'U')
        {
            last_y --;
        }
        else if(bombDir[0] == 'D')
        {
            first_y ++;
        }
        if(bombDir[1] =='L')
        {
            last_x--;

        }
        else if(bombDir[1] == 'R')
        {
           first_x ++;
        }
    X0 = first_x + (last_x-first_x)/2;
    Y0 = first_y + (last_y - first_y)/2;
    cout <<X0<<" "<<Y0<< endl;   
    }
   

    return 0;
}