View Compilation Error

0_0_29850831_1731.cpp: In function 'int main()':
0_0_29850831_1731.cpp:40:18: error: 'i' was not declared in this scope
    double le = a[i].loc, ri = a[i + 1].loc , mil, mir;
                  ^
0_0_29850831_1731.cpp:41:21: error: 'ri' was not declared in this scope
    while(le + eps < ri)
                     ^
0_0_29850831_1731.cpp:43:5: error: 'mil' was not declared in this scope
     mil = (le*5 + ri*4)/9;
     ^
0_0_29850831_1731.cpp:44:5: error: 'mir' was not declared in this scope
     mir = (le*4 + ri*5)/9;
     ^