Compilare: user.cpp: In function ‘unsigned int suma(unsigned int, unsigned int)’: user.cpp:12:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=a; i<=b; i++) ^ user.cpp: In function ‘int main()’: user.cpp:20:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=1; i<=n; i++) ^ user.cpp:25:13: warning: left operand of comma operator has no effect [-Wunused-value] s2=(3,n-1); ^ user.cpp:27:13: warning: left operand of comma operator has no effect [-Wunused-value] s3=(3,n-2); ^