/in/foo.c: In function 'iS':
/in/foo.c:5:46: warning: operation on 'j' may be undefined [-Wsequence-point]
 while(i<n){t=a[i],j=i++;while(j&&a[j-1]>t)a[j--]=a[j];a[j]=t;}}
                                             ~^~
/in/foo.c: In function 'main':
/in/foo.c:16:20: warning: unused variable 'f' [-Wunused-variable]
 int main(){int i,j,f=1;
                    ^