foo.cc: In function 'void solve()':
foo.cc:7:5: error: 'string' was not declared in this scope
     string s;cin>>s;
     ^~~~~~
foo.cc:7:5: note: suggested alternative: 'struct'
     string s;cin>>s;
     ^~~~~~
     struct
foo.cc:7:14: error: 'cin' was not declared in this scope
     string s;cin>>s;
              ^~~
foo.cc:7:19: error: 's' was not declared in this scope
     string s;cin>>s;
                   ^
foo.cc:12:25: error: 'm' was not declared in this scope
     if(h>=0 && h<=23 && m>=0 && m<=59) 
                         ^
foo.cc:13:9: error: 'printf' was not declared in this scope
         printf("%02d:%02d\n", h, m);
         ^~~~~~
foo.cc:13:9: note: suggested alternative: 'int'
         printf("%02d:%02d\n", h, m);
         ^~~~~~
         int
foo.cc:15:9: error: 'printf' was not declared in this scope
         printf("it's not a valid time\n");  
         ^~~~~~
foo.cc:15:9: note: suggested alternative: 'int'
         printf("it's not a valid time\n");  
         ^~~~~~
         int

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