View Compilation Error

0_0_15968280_658.cpp: In function 'int main()':
0_0_15968280_658.cpp:15:38: error: 'strlen' was not declared in this scope
         for(int i = 0; i < strlen(str); i++) {
                                      ^
0_0_15968280_658.cpp:17:53: error: 'min' was not declared in this scope
                 Min = min(Min, i - pre[str[i] - 'a']);
                                                     ^