Compilare: main.cpp: In function 'int main()': main.cpp:30:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i=0; i<s1.size(); i++){ ~^~~~~~~~~~ main.cpp:34:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i=0; i<s2.size(); i++){ ~^~~~~~~~~~