Compilare: user.cpp: In function 'int solve(int, int, int, int)': user.cpp:44: warning: unused variable 'ret' user.cpp: In function 'int main()': user.cpp:78: warning: unused variable 'a1' user.cpp: In function 'int solve(int, int, int, int)': user.cpp:67: warning: control reaches end of non-void function