Look at my source:

#include <stdio.h>

#define M 200

int scr[M][M] = {0};
int scrb[M][M] = {0};
int N;

struct el_t {
    int x, y;
    el_t * n;
};

el_t * beg = 0;

void add(int x, int y)
{
    scrb[x][y] = 1;
    if (!beg){
        beg = new el_t;
        beg->x = x;
        beg->y = y;
        beg->n = 0;
        return;
    }
    el_t * t = beg;
    while (t->n) t = t->n;
    t->n = new el_t;
    t->n->x = x;
    t->n->y = y;
    t->n->n = 0;
}

int main ()
{
    scanf ("%d", &N);
    int fx, fy;
    for (int i =0; i < N; i++){
        int x, y;
        scanf ("%d %d", &x, &y);
        scr [x][y] = 1;
        if(!i){
            add (x, y);
            fx = x;
            fy =y;
        }
    }
    printf ("%d %d\n", fx, fy);

    while (beg){
        int tx = beg->x, ty = beg->y;

        int x = tx + 1, y = ty;
        if (scr[x][y] && !scrb[x][y]){
            add (x, y);
            printf ("R");
        }

        x = tx, y = ty + 1;
        if (scr[x][y] && !scrb[x][y]){
            add (x, y);
            printf ("T");
        }

        x = tx - 1, y = ty;
        if (scr[x][y] && !scrb[x][y]){
            add (x, y);
            printf ("L");
        }

        x = tx , y = ty - 1;
        if (scr[x][y] && !scrb[x][y]){
            add (x, y);
            printf ("B");
        }

        if (beg->n) printf (",\n");
        else printf (".\n");
        beg = beg->n;
    }


    return 0;
}