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

#define LINE_MAX_LENGTH 256

typedef enum tile_type {
    GARDEN_PLOT,
    ROCK,
    WALKED,
} tile_type_t;

int main(int argc, char *argv[]) {
    if (argc != 2) {
        fprintf(stderr, "Please specify the step number\n"); 
        return 1;
    }
    int step_number = 0;
    sscanf(argv[1], "%i", &step_number); 
    char *p, *buf, c;

    tile_type_t map[LINE_MAX_LENGTH][LINE_MAX_LENGTH];
    int x = 0, y = 0;

    buf = (char *)malloc(LINE_MAX_LENGTH);
    memset(buf, 0, LINE_MAX_LENGTH);
    p = buf;

    int start[2];

    while ((c = getchar()) != EOF) {
        *p++ = c;
        if (c == '\n') {
            p = buf;
            x = 0;
            while (*p != '\n') {
                switch (*p) {
                    case '.':
                        map[x][y] = GARDEN_PLOT;
                        break;
                    case '#':
                        map[x][y] = ROCK;
                        break;
                    case 'S':
                        map[x][y] = GARDEN_PLOT;
                        start[0] = x;
                        start[1] = y;
                        break;
                }
                x++;
                p++;
            }
            y++;
            memset(buf, 0, LINE_MAX_LENGTH);
            p = buf;
        }
    }

    tile_type_t walked_curr[LINE_MAX_LENGTH][LINE_MAX_LENGTH], walked_next[LINE_MAX_LENGTH][LINE_MAX_LENGTH];
    memcpy(walked_curr, map, sizeof(map));
    walked_curr[start[0]][start[1]] = WALKED;

    for (int i = 0; i < step_number; i++) {
        memcpy(walked_next, map, sizeof(map));
        for (int j = 0; j < y; j++) {
            for (int k = 0; k < x; k++) {
                if (walked_curr[k][j] == WALKED) {
                    // UP
                    if (j > 0 && walked_next[k][j-1] == GARDEN_PLOT) {
                        walked_next[k][j-1] = WALKED;
                    }
                    // LEFT
                    if (k > 0 && walked_next[k-1][j] == GARDEN_PLOT) {
                        walked_next[k-1][j] = WALKED;
                    }
                    // DOWN
                    if (j < y - 1 && walked_next[k][j+1] == GARDEN_PLOT) {
                        walked_next[k][j+1] = WALKED;
                    }
                    // RIGHT
                    if (k < x - 1 && walked_next[k+1][j] == GARDEN_PLOT) {
                        walked_next[k+1][j] = WALKED;
                    }
                }
            }
        }
        memcpy(walked_curr, walked_next, sizeof(map));
    }

    int part1 = 0;

    for (int i = 0; i < y; i++) {
        for (int j = 0; j < x; j++) {
            if (walked_curr[j][i] == WALKED) {
                part1++;
            }
        }
    }

    printf("%i\n", part1);
    free(buf);
}