Compilare: user.c: In function ‘maxim’: user.c:13:2: warning: implicit declaration of function ‘abs’ [-Wimplicit-function-declaration] int rez1 = abs(A.x - B.x); ^ user.c: In function ‘main’: user.c:24:9: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result [-Wunused-result] freopen("distancesum.in", "r", stdin); ^ user.c:25:9: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result [-Wunused-result] freopen("distancesum.out", "w", stdout); ^ user.c:27:7: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d", &n, &m); ^ user.c:30:8: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &A[i].x); ^ user.c:31:8: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &A[i].y); ^ user.c:35:8: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &B[i].x); ^ user.c:36:8: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &B[i].y); ^