Compilare: main.c: In function 'main': main.c:31:11: warning: implicit declaration of function 'abs' [-Wimplicit-function-declaration] x=abs(a-b); ^~~ main.c:13:5: warning: ignoring return value of 'fscanf', declared with attribute warn_unused_result [-Wunused-result] fscanf(fptr, "%d", &a); ^~~~~~~~~~~~~~~~~~~~~~ main.c:14:5: warning: ignoring return value of 'fscanf', declared with attribute warn_unused_result [-Wunused-result] fscanf(fptr, "%d", &b); ^~~~~~~~~~~~~~~~~~~~~~