foo.cpp: In function 'int search(int)':
foo.cpp:27:5: warning: no return statement in function returning non-void [-Wreturn-type]
     }
     ^
foo.cpp: In function 'int main()':
foo.cpp:30:29: error: 'stdin' was not declared in this scope
     freopen("prison.in","r",stdin);
                             ^
foo.cpp:30:34: error: 'freopen' was not declared in this scope
     freopen("prison.in","r",stdin);
                                  ^
foo.cpp:31:30: error: 'stdout' was not declared in this scope
     freopen("prison.out","w",stdout);
                              ^
foo.cpp:32:28: error: 'memset' was not declared in this scope
     memset(a,true,sizeof(a));
                            ^