Compilare: main.cpp: In function 'int main()': main.cpp:31:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(r=0;r<u[y][t].size();r++) ~^~~~~~~~~~~~~~~ main.cpp:47:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(r=0;r<u[y][t].size();r++) ~^~~~~~~~~~~~~~~ main.cpp:59:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(j=0;j<u[i][1].size();j++) ~^~~~~~~~~~~~~~~ main.cpp:65:25: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(t=0;t<u[i][r].size();t++) ~^~~~~~~~~~~~~~~