2d search O(log n)

#include <stdio.h>
#include <stdlib.h>

int main()
{
    int mat[n][m];
    int t=n-1, b = 0, l = 0, r = m -1, flag = 0,num; //num is the we search for

    while(t>=b && l <= r)
    {
        if(mat[t/2][r/2]<num)
        {
            break;
        }
        if(mat[t/2][r/2]==num)
        {
            printf("[%d %d]",t/2,r/2);
            flag = 1;
            break;
        }
        if(mat[t][r/2] == num)
        {
            printf("[%d %d]",t,r/2);
            flag = 1;
            break;
        }
        if(mat[t/2][r] == num)
        {
            printf("[%d %d]",t/2,r);
            flag = 1;
            break;
        }
        if(mat[t/2][0] == num)
        {
            printf("[%d %d]",t/2,0);
            flag = 1;
            break;
        }
        if(mat[0][r/2] == num)
        {
            printf("[%d %d]",0,r/2);
            flag = 1;
            break;
        }
        if(mat[t/2][r/2] > num)   //first quarter
        {
            t=t/2;
            r=r/2;
            continue;
        }
        else if(a[t/2][0] > num)   //second quarter
        {
            t=t/2;
            l=r/2;
            continue;
        }
        else if(a[0][r/2] > num)   //third quarter
        {
            b=t/2;
            r=r/2;
            continue;
        }
        else if(a[0][r/2] > num)   //fourth quarter
        {
            b=t/2;
            l=r/2;
            continue;
        }
    }
    if(!flag) printf("NOT FOUND");
}