Compilare: user.cpp: In function ‘void multiply(long long unsigned int)’: user.cpp:9:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=1; i<=number[0]; i++) ^ user.cpp: In function ‘int main()’: user.cpp:54:24: warning: unused variable ‘sum’ [-Wunused-variable] unsigned long long n, sum; ^