Compilare: main.cpp: In function 'long long int aduna(int, int)': main.cpp:46:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int c1=0; c1<a[xx][yy].size(); c1++) ~~^~~~~~~~~~~~~~~~~ main.cpp: In function 'int main()': main.cpp:68:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int c=0; c<a[i][j].size(); c++) ~^~~~~~~~~~~~~~~