Compilare: main.c: In function 'add_edge': main.c:25:1: warning: control reaches end of non-void function [-Wreturn-type] } ^ main.c: In function 'main': main.c:45:5: warning: ignoring return value of 'freopen', declared with attribute warn_unused_result [-Wunused-result] freopen("alpin.in", "r", stdin); ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ main.c:46:5: warning: ignoring return value of 'freopen', declared with attribute warn_unused_result [-Wunused-result] freopen("alpin.out", "w", stdout); ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ main.c:49:5: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &n); ^~~~~~~~~~~~~~~ main.c:53:13: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &graph_matrix[i][j]); ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~