#include <stdio.h>

int sum(int n){ 
int i;
int s = 0;

for (i = 1; i <= n; i++) {
s = s + i;   }

return s;
  
  }

int main(void) {
	int a,b;
    a = 10;
    b = sum(a);
    printf("1から%dまでの和は%d", a,b );
	return 0;
}