Compilare: user.cpp: In function ‘int main()’: user.cpp:15:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(s.size()<=n && s.size()!=0) ^ user.cpp:51:43: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=n-nr-1;i<s.size();++i) ^ user.cpp:73:43: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=n-nr+1;i<s.size();++i) ^ user.cpp:8:11: warning: unused variable ‘m’ [-Wunused-variable] int n,m,i,j,nr=1,l=0; ^