Compilare: user.cpp: In function ‘int main()’: user.cpp:16:13: warning: unused variable ‘op’ [-Wunused-variable] int op = 0, NR = 0, Sum = 0; ^ user.cpp:8:39: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("matricen.in", "r", stdin); ^ user.cpp:9:41: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("matricen.out", "w", stdout); ^ user.cpp:10:26: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d", &n, &q); ^ user.cpp:13:71: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &a[i][j]), sum[i][j] = sum[i][j - 1] + a[i][j]; ^ user.cpp:15:46: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d%d%d", &l1, &c1, &l2, &c2); ^