from collections import defaultdict

def gridlandMetro(n, m, k, track):
    
    row_record = defaultdict(list)
    for r, c1, c2 in track:
        if r not in row_record:
            row_record[r] = [c1, c2]
        else:
            st, ed = row_record[r][0], row_record[r][1]
            if c1 > ed:
                row_record[r][1] += c2 - c1 + 1
            else:
                row_record[r][1] = max(ed, c2)
            if c2 < st:
                row_record[r][0] -= c2 - c1 + 1
            else:
                row_record[r][0] = min(st, c1)
            
    total_num = n * m
    for st, ed in row_record.values():
        total_num -= ed - st + 1
        
    return total_num