foo.cpp: In function 'int main()':
foo.cpp:19:11: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
     cin>>a+1>>b+1;
           ^
foo.cpp:19:16: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
     cin>>a+1>>b+1;
                ^
foo.cpp:20:24: error: 'strlen' was not declared in this scope
     int ln = strlen(a+1);
                        ^