Compilare: user.cpp: In function 'long int solve(long int, long int, long int, long int)': user.cpp:61: warning: unused variable 'ret' user.cpp: In function 'int main()': user.cpp:95: warning: unused variable 'a1' user.cpp: In function 'long int solve(long int, long int, long int, long int)': user.cpp:84: warning: control reaches end of non-void function