Compilare: main.cpp: In function 'int main()': main.cpp:38:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(j=1; j<c[i].length(); j++) ~^~~~~~~~~~~~~~ main.cpp:48:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(j=0; j<a.length(); j++) ~^~~~~~~~~~~ main.cpp:54:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(k==c[i].length()) ~^~~~~~~~~~~~~~~ main.cpp:61:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(j=0;j<c[i].length();j++) ~^~~~~~~~~~~~~~