Compilare: main.cpp: In function 'void topo(int)': main.cpp:31:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for ( i = 0; i < G[x].size(); ++i ) ~~^~~~~~~~~~~~~ main.cpp: In function 'void DFS(int)': main.cpp:42:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for ( i = 0; i < Gt[x].size(); ++i ) ~~^~~~~~~~~~~~~~ main.cpp: In function 'void solve()': main.cpp:63:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for ( j = 0; j < comp[i].size(); ++j ) ~~^~~~~~~~~~~~~~~~ main.cpp:49:15: warning: unused variable 'x' [-Wunused-variable] int i, j, x; ^