foo.cpp: In function 'int main()':
foo.cpp:8:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int i=0;i<tot.length() && tot[i]!='E';i++){
                 ~^~~~~~~~~~~~~
foo.cpp:18:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int i=0;i<tot.length() && tot[i]!='E';i++){
                 ~^~~~~~~~~~~~~