View Compilation Error

0_0_33578591_15692.cpp: In function 'long long int fun(pii, pii, pii)':
0_0_33578591_15692.cpp:21:21: error: expression cannot be used as a function
     return (b.first()-c.first)*(b.second-a.second)-(a.first-b.first)*(c.second-b.second)<=0;
                     ^