View Compilation Error

0_0_28170437_5221.cpp:4:1: error: expected ',' or ';' before 'int'
 int dfs(int l,int r)
 ^
0_0_28170437_5221.cpp: In function 'int main()':
0_0_28170437_5221.cpp:16:23: error: 'dfs' was not declared in this scope
         int t =dfs(l,r);if(t==0x7f7f7f7f)t=-1;
                       ^