Main.cc: In function ‘int cal(int)’: Main.cc:17:1: warning: no return statement in function returning non-void [-Wreturn-type] } ^ Main.cc: In function ‘int main()’: Main.cc:36:24: error: no matching function for call to ‘max(int, long long int)’ cout< const _Tp& std::max(const _Tp&, const _Tp&) max(const _Tp& __a, const _Tp& __b) ^~~ /usr/include/c++/7/bits/stl_algobase.h:219:5: note: template argument deduction/substitution failed: Main.cc:36:24: note: deduced conflicting types for parameter ‘const _Tp’ (‘int’ and ‘long long int’) cout< const _Tp& std::max(const _Tp&, const _Tp&, _Compare) max(const _Tp& __a, const _Tp& __b, _Compare __comp) ^~~ /usr/include/c++/7/bits/stl_algobase.h:265:5: note: template argument deduction/substitution failed: Main.cc:36:24: note: deduced conflicting types for parameter ‘const _Tp’ (‘int’ and ‘long long int’) cout< _Tp std::max(std::initializer_list<_Tp>) max(initializer_list<_Tp> __l) ^~~ /usr/include/c++/7/bits/stl_algo.h:3462:5: note: template argument deduction/substitution failed: Main.cc:36:24: note: mismatched types ‘std::initializer_list<_Tp>’ and ‘int’ cout< _Tp std::max(std::initializer_list<_Tp>, _Compare) max(initializer_list<_Tp> __l, _Compare __comp) ^~~ /usr/include/c++/7/bits/stl_algo.h:3468:5: note: template argument deduction/substitution failed: Main.cc:36:24: note: mismatched types ‘std::initializer_list<_Tp>’ and ‘int’ cout<