Compilare: main.cpp: In function 'int main()': main.cpp:14:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0; i<strlen(s1); i++) ~^~~~~~~~~~~ main.cpp:16:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j=0; j<strlen(s2); j++) ~^~~~~~~~~~~