Compilare: main.c:19:6: warning: return type of 'main' is not 'int' [-Wmain] void main() { ^~~~ main.c: In function 'check': main.c:16:1: warning: control reaches end of non-void function [-Wreturn-type] } ^ main.c: In function 'main': main.c:22:3: warning: ignoring return value of 'fscanf', declared with attribute warn_unused_result [-Wunused-result] fscanf(fp, "%d", &P); ^~~~~~~~~~~~~~~~~~~~