Compilare: user.cpp: In function ‘int main()’: user.cpp:6:33: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("100m.in", "r", stdin);freopen("100m.out", "w", stdout);int n;scanf("%d", &n);a[1][1] = 1;for (int i = 2; i <= n; ++i){int p = i & 1;a[p][1] = 1; ^ user.cpp:6:66: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("100m.in", "r", stdin);freopen("100m.out", "w", stdout);int n;scanf("%d", &n);a[1][1] = 1;for (int i = 2; i <= n; ++i){int p = i & 1;a[p][1] = 1; ^ user.cpp:6:88: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] freopen("100m.in", "r", stdin);freopen("100m.out", "w", stdout);int n;scanf("%d", &n);a[1][1] = 1;for (int i = 2; i <= n; ++i){int p = i & 1;a[p][1] = 1; ^