#include <stdio.h>

int m,n,a[4100][4100],nr=0;

int main()
{int i,j,k;
FILE *f;
f=fopen("triplete.in","r");
fscanf(f,"%d %d",&m,&n);
for (k=1;k<=n;k++)
    {fscanf(f,"%d %d",&i,&j);
    a[i][j]=1;
    }
fclose(f);
for (i=0;i<=n;i++)
    a[i][0]=a[0][i]=1;

for (i=2;i<=m;i++)
    for (j=i+1;j<=m;j++)
        {if (a[i][j])
            if (a[i-1][j-1]&&a[i-1][j])
               nr++;
        }
FILE *g;
g=fopen("triplete.out","w");
fprintf(g,"%d",nr);
fclose(g);
    }