Compilare: main.cpp: In function 'int main()': main.cpp:51:14: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0;i<el.size();i++) ~^~~~~~~~~~ main.cpp:52:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(j=i+1;j<el.size();j++){ ~^~~~~~~~~~ main.cpp:55:24: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(k=j+1;k<el.size();k++) ~^~~~~~~~~~