2021/03/29
2020 KB
0 ms
#include <iostream>
int blocks[502];
int H, W;
int ans;
void input_faster()
{
std::ios_base::sync_with_stdio(false);
std::cin.tie(0);
std::cout.tie(0);
}
void input()
{
input_faster();
std::cin >> H >> W;
for (int i = 0 ; i < W ; i++)
std::cin >> blocks[i];
}
void solve()
{
int l_block;
for (int i = 1 ; i <= H ; i++)
{
l_block = -1;
for (int j = 0 ; j < W ; j++)
{
if (blocks[j] >= i)
{
if (l_block == -1)
{
l_block = j;
continue;
}
ans += (j - l_block - 1);
l_block = j;
}
}
}
}
void print_val()
{
std::cout << ans;
}
int main()
{
input();
solve();
print_val();
return (0);
}