/in/lab4.c: In function 'main':
/in/lab4.c:49:26: warning: format not a string literal and no format arguments [-Wformat-security]
             }else printf(strff);
                          ^~~~~
/in/lab4.c: In function 'expcalculate':
/in/lab4.c:173:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for (i=0,j=0,k=0;i<strlen(exp);i++){
                       ^