View Compilation Error

0_0_24950591_3641.cpp: In function 'int main()':
0_0_24950591_3641.cpp:20:12: error: 'i' was not declared in this scope
         f1(i, 1, n) {
            ^
0_0_24950591_3641.cpp:20:19: error: 'f1' was not declared in this scope
         f1(i, 1, n) {
                   ^