View Compilation Error

0_0_33377118_28242.cpp: In function 'int sol()':
0_0_33377118_28242.cpp:171:17: error: 'build' was not declared in this scope
  build(1, 1, n+1);
                 ^
0_0_33377118_28242.cpp:190:17: error: 'an' was not declared in this scope
  printf("%d\n", an
                 ^
0_0_33377118_28242.cpp:190:17: error: expected '}' at end of input