Compilare: main.cpp: In function 'int main()': main.cpp:10:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<s.size()-1;++i) ~^~~~~~~~~~~ main.cpp:11:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j=i+1;j<s.size();++j) ~^~~~~~~~~ main.cpp:16:24: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int k=i+1;k<s.size();++k) ~^~~~~~~~~ main.cpp:20:24: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int k=j+1;k<s.size();++k) ~^~~~~~~~~