Compilare: user.cpp: In function ‘int main()’: user.cpp:45:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0;i<strlen(S);i++){ ^ user.cpp: In function ‘int imp(int, int, int, int)’: user.cpp:41:1: warning: control reaches end of non-void function [-Wreturn-type] } ^