Compilare: main.cpp: In function 'int main()': main.cpp:33:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(j=1; j<c[i].length(); j++) ~^~~~~~~~~~~~~~ main.cpp:43:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(j=0; j<a.length(); j++) ~^~~~~~~~~~~ main.cpp:49:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(k==c[i].length()) ~^~~~~~~~~~~~~~~