Compilare: user.cpp: In function ‘int main()’: user.cpp:12:42: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("infinitywar.in", "r", stdin); ^ user.cpp:13:44: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("infinitywar.out", "w", stdout); ^ user.cpp:15:26: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d", &n, &q); ^ user.cpp:18:27: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &l[i]); ^ user.cpp:20:52: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] for(j=0; j<l[i]; ++j) scanf("%d", &v[i][j]); ^ user.cpp:24:52: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] for(i=1; i<=q; ++i) scanf("%d%d", &x[i], &y[i]); ^