/in/foo.cc: In function 'int main()':
/in/foo.cc:45:55: warning: comparison of constant '0' with boolean expression is always false [-Wbool-compare]
     if(line[head] * 2 > maxn || line[head] * 2 > maxn < 0)
                                 ~~~~~~~~~~~~~~~~~~~~~~^~~
/in/foo.cc:45:48: warning: comparisons like 'X<=Y<=Z' do not have their mathematical meaning [-Wparentheses]
     if(line[head] * 2 > maxn || line[head] * 2 > maxn < 0)
                                 ~~~~~~~~~~~~~~~^~~~~~