View Compilation Error

0_0_17980664_2967.cpp: In function 'long long int dfs(long long int, long long int, long long int, long long int)':
0_0_17980664_2967.cpp:20:18: error: expected primary-expression before 'long'
  long long pre = long long(log(p - q+1) / log(2));
                  ^