Main.cc: In function 'int main()':
Main.cc:7:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
for(int i=0;i<s.size();i++)
^
Main.cc:10:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
for(int i=0;i<s.size();i++){
^
Main.cc:11:54: error: expected ';' before '}' token
if(a[s[i]-'a']==1) {cout<<s[i]<<endl;return 0}
^