View Compilation Error

0_0_30425602_30992.cpp: In function '__int128 solve(long long int)':
0_0_30425602_30992.cpp:13:79: error: 'calc' was not declared in this scope
     if(n % 2 == 0) return min(n*n*n*b+(n-1)*n*n*a, 18*(n/2)*(n/2)*a+7*calc(n/2));
                                                                               ^