Compilare: main.cpp: In function 'bool ok(int, int)': main.cpp:47:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < v.size(); i++) ~~^~~~~~~~~~ main.cpp: In function 'int main()': main.cpp:76:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 1; i < xx.size(); i++) ~~^~~~~~~~~~~ main.cpp:77:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j = 1; j < yy.size(); j++) ~~^~~~~~~~~~~ main.cpp:87:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 1; i < xx.size(); i++) ~~^~~~~~~~~~~ main.cpp:88:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j = 1; j < yy.size(); j++) ~~^~~~~~~~~~~