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#include <iostream>
//#include <gtest/gtest.h>
const int FIB_PISANO_PERIOD_FOR_TEN = 60;
static int getFibNModM(long n) {
long r = n % FIB_PISANO_PERIOD_FOR_TEN;
if (r == 0)
return 0;
int firstN = 0;
int secondN = 1;
int tempHolder = 1;
for (int i = 1; i < r; i++) {
tempHolder = (firstN + secondN) % 10;
firstN = secondN;
secondN = tempHolder;
}
return secondN;
}
static int getLastDigit(long n) {
if (n <= 1)
return (int) n;
int result = getFibNModM(n + 2);
if (result == 0)
return 9;
else
return result - 1;
}
static int getLastDigit(long m, long n) {
if (m == n)
return getFibNModM(n);
else {
int sumFn = getLastDigit(n);
int sumFm;
if (m <= 1)
sumFm = 0;
else
sumFm = getLastDigit(m - 1);
if (sumFn >= sumFm)
return sumFn - sumFm;
else
return sumFn - sumFm + 10;
}
}
//TEST(FibPartialSumLastDigit, Five_Five) {
// ASSERT_EQ(getLastDigit(5, 5), 5);
//}
//
//TEST(FibPartialSumLastDigit, Ten_200) {
// ASSERT_EQ(getLastDigit(10, 200), 2);
//}
//
//TEST(FibPartialSumLastDigit, One_2) {
// ASSERT_EQ(getLastDigit(1, 2), 2);
//}
int main() {
long m, n;
std::cin >> m;
std::cin >> n;
int c = getLastDigit(m, n);
std::cout << c << '\n';
}
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