foo.cc: In function 'int main()':
foo.cc:45:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int i = 0;i < strlen(str);i++)
                   ~~^~~~~~~~~~~~~
foo.cc:43:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d%d%d\n",&p1,&p2,&p3);
     ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~