View Compilation Error

0_0_34380723_153.cpp:119:17: error: stray '`' in program
                 ans -= (t + 1) * (he[i] - he[i - 1]);`
                 ^
0_0_34380723_153.cpp: In function 'int main()':
0_0_34380723_153.cpp:144:12: error: 'AC' was not declared in this scope
     return AC;
            ^