Each new term in the Fibonacci sequence is generated by adding the previous two terms. By starting with 1 and 2, the first 10 terms will be:

1, 2, 3, 5, 8, 13, 21, 34, 55, 89, ...

By considering the terms in the Fibonacci sequence whose values do not exceed four million, find the sum of the even-valued terms.

```
package main
import (
"fmt"
"time"
)
func main() {
start := time.Now()
i, c, sum := [...]int{1, 1}, 0, 0
for c < 4e6 {
c = i[0] + i[1]
i[0] = i[1]
i[1] = c
if c%2 == 0 {
sum += c
}
}
fmt.Println("Execution time: ", time.Since(start))
fmt.Print(sum, "\n")
}
```

Execution time: **276ns**

Answer: **4613732**