Compilare: main.cpp: In function 'int euler(int)': main.cpp:34:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (j=0;j<=x[csp].sz.size()-1;++j) ~^~~~~~~~~~~~~~~~~~~~ main.cpp:45:1: warning: no return statement in function returning non-void [-Wreturn-type] } ^ main.cpp: In function 'int main()': main.cpp:58:47: warning: narrowing conversion of 'x.std::vector<_Tp, _Alloc>::operator[]<adat, std::allocator<adat> >(((std::vector<adat>::size_type)b)).adat::sz.std::vector<_Tp, _Alloc>::size<el, std::allocator<el> >()' from 'std::vector<el>::size_type {aka long unsigned int}' to 'int' inside { } [-Wnarrowing] x[a].sz.push_back({b,x[b].sz.size(),false}); ~~~~~~~~~~~~^~ main.cpp:59:49: warning: narrowing conversion of '(x.std::vector<_Tp, _Alloc>::operator[]<adat, std::allocator<adat> >(((std::vector<adat>::size_type)a)).adat::sz.std::vector<_Tp, _Alloc>::size<el, std::allocator<el> >() - 1ul)' from 'std::vector<el>::size_type {aka long unsigned int}' to 'int' inside { } [-Wnarrowing] x[b].sz.push_back({a,x[a].sz.size()-1,false}); ~~~~~~~~~~~~~~^~ main.cpp:63:49: warning: narrowing conversion of '(x.std::vector<_Tp, _Alloc>::operator[]<adat, std::allocator<adat> >(((std::vector<adat>::size_type)b)).adat::sz.std::vector<_Tp, _Alloc>::size<el, std::allocator<el> >() + 1ul)' from 'std::vector<el>::size_type {aka long unsigned int}' to 'int' inside { } [-Wnarrowing] x[a].sz.push_back({b,x[b].sz.size()+1,false}); ~~~~~~~~~~~~~~^~ main.cpp:64:49: warning: narrowing conversion of '(x.std::vector<_Tp, _Alloc>::operator[]<adat, std::allocator<adat> >(((std::vector<adat>::size_type)b)).adat::sz.std::vector<_Tp, _Alloc>::size<el, std::allocator<el> >() - 1ul)' from 'std::vector<el>::size_type {aka long unsigned int}' to 'int' inside { } [-Wnarrowing] x[b].sz.push_back({a,x[b].sz.size()-1,false}); ~~~~~~~~~~~~~~^~