src.cpp: In function 'int main()':
src.cpp:7:16: error: redeclaration of 'std::ifstream f1'
ifstream f1("DUAXE.OUT");
^
src.cpp:6:14: note: 'std::ifstream f1' previously declared here
ifstream f1("DUAXE.INP");
^
src.cpp:15:5: error: 'f2' was not declared in this scope
f2<<dem;
^