Compilare: main.cpp: In function 'int main()': main.cpp:81:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=1;i<s.size();++i) ~^~~~~~~~~ main.cpp:87:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<s.size();++i) ~^~~~~~~~~ main.cpp:42:19: warning: variable 'nn' set but not used [-Wunused-but-set-variable] long long nn=0; ^~ main.cpp:43:19: warning: variable 'o' set but not used [-Wunused-but-set-variable] long long o=0; ^