Compilare: user.cpp: In function ‘int main()’: user.cpp:73:51: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(t = 0; t < prequisite[j].size() && OK; t++) { ^ user.cpp:45:37: warning: unused variable ‘x’ [-Wunused-variable] int n, k, i, j, t, a, b, m = 0, x, y; ^ user.cpp:45:40: warning: unused variable ‘y’ [-Wunused-variable] int n, k, i, j, t, a, b, m = 0, x, y; ^