Eroare de compilare: user.c: In function ‘main’: user.c:5:5: warning: implicit declaration of function ‘freopen’ [-Wimplicit-function-declaration] freopen("adunare.in","r",stdin); ^~~~~~~ user.c:5:30: error: ‘stdin’ undeclared (first use in this function) freopen("adunare.in","r",stdin); ^~~~~ user.c:5:30: note: each undeclared identifier is reported only once for each function it appears in user.c:6:31: error: ‘stdout’ undeclared (first use in this function) freopen("adunare.out","w",stdout); ^~~~~~ user.c:7:5: warning: implicit declaration of function ‘scanf’ [-Wimplicit-function-declaration] scanf("%d",&a); ^~~~~ user.c:7:5: warning: incompatible implicit declaration of built-in function ‘scanf’ user.c:7:5: note: include ‘<stdio.h>’ or provide a declaration of ‘scanf’ user.c:10:5: warning: implicit declaration of function ‘printf’ [-Wimplicit-function-declaration] printf("%d",s) ^~~~~~ user.c:10:5: warning: incompatible implicit declaration of built-in function ‘printf’ user.c:10:5: note: include ‘<stdio.h>’ or provide a declaration of ‘printf’ user.c:11:5: error: expected ‘;’ before ‘return’ return 0; ^~~~~~