Compilare: main.cpp: In function 'int main()': main.cpp:65:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i2 = 0; i2 < pos[i][j].size(); ++i2) { ~~~^~~~~~~~~~~~~~~~~~ main.cpp:72:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i2 = 0; i2 < pos[i][j].size(); ++i2) { ~~~^~~~~~~~~~~~~~~~~~ main.cpp:82:33: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i2 = 0; i2 < pos[i][j].size(); ++i2) ~~~^~~~~~~~~~~~~~~~~~