Compilare: user.cpp: In function ‘int main()’: user.cpp:36:40: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(f, "%d%d%d%d", &n, &m, &q, &k); ^ user.cpp:38:54: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(f, "%d%d%d%d%d", &x1, &y1, &x2, &y2, &val); ^ user.cpp:17:14: warning: ‘x’ may be used uninitialized in this function [-Wmaybe-uninitialized] a[x][y] = 0; ^ user.cpp:14:7: note: ‘x’ was declared here int x, y, cnt; ^ user.cpp:17:14: warning: ‘y’ may be used uninitialized in this function [-Wmaybe-uninitialized] a[x][y] = 0; ^ user.cpp:14:10: note: ‘y’ was declared here int x, y, cnt; ^