foo.cc: In function 'int main()':
foo.cc:9:15: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
    9 |         cin>>s+1>>f+1;
      |              ~^~
foo.cc:9:20: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
    9 |         cin>>s+1>>f+1;
      |                   ~^~

[Hydro](https://hydro.ac)提供评测服务