Compilare: main.cpp: In function 'int main()': main.cpp:12:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for ( i = 0; i < a.size(); i++ ) { ~~^~~~~~~~~~ main.cpp:15:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for ( i = 0; i < b.size(); i++ ) { ~~^~~~~~~~~~ main.cpp:25:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for ( i = 0; i < a.size(); i++ ) { ~~^~~~~~~~~~ main.cpp:43:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for ( i = 0; i < b.size(); i++ ) { ~~^~~~~~~~~~