#include <iostream>     // std::cout
#include <functional>   // std::minus, std::divides
#include <numeric>      // std::inner_product
 
unsigned myaccumulator (unsigned x, unsigned y) {return x+y;}
unsigned myLessThan (unsigned x, unsigned y) {return x<y;}
 
int main () {
  unsigned init = 0;
  unsigned series1[] = {10,20,30};
  unsigned series2[] = {1,2,3};
 
  std::cout << "using default inner_product: ";
  std::cout << std::inner_product(series1,series1+3,series2,init);
  std::cout << '\n';
 
 
  std::cout << "using custom functions: ";
  std::cout << std::inner_product(series1,series1+2,series1 + 1,init,
                                  myaccumulator,myLessThan);
  std::cout << '\n';
 
  return 0;
}

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