0_0_30123511_5131.cpp: In function 'int main()': 0_0_30123511_5131.cpp:57:28: error: too few arguments to function 'bool cmp(node, node)' sort(f+1,f+1+n,cmp()); ^ 0_0_30123511_5131.cpp:30:6: note: declared here bool cmp(node x1,node x2) ^