Compilare: user.cpp: In function 'void back(long int, long int)': user.cpp:12: warning: unused variable 'a1' user.cpp:12: warning: unused variable 'a2' user.cpp: In function 'int main()': user.cpp:65: warning: format '%d' expects type 'int*', but argument 2 has type 'long int*' user.cpp:81: warning: format '%d' expects type 'int', but argument 2 has type 'long int' /tmp/ccsXQeX2.o: In function `main': user.cpp:(.text+0x2ca): warning: the `gets' function is dangerous and should not be used.